refactor(ci): Bypass Lerna and repurpose the 'test-travis' run-script (#129)

## Summary

- Bypass Lerna things in CI
- Don't install `grunt`. I presume it was installed because `test-travis` refers to it, but locally-installed executable modules are on the $PATH in run-scripts so global installation is unnecessary.
- Rename `test-travis` to `test-xbrowser` and modify it such that it only runs cross-browser tests in BrowserStack (via `grunt`), rather than re-running unit tests headlessly+locally _again_ with `npm test` (which is done as part of the `prepare` lifecycle hook that's invoked during `npm install`). The rename makes it clearer that the run-script could plausibly, usefully be run locally as well (say, if one was debugging a consistent failure in some browser).

Lerna seems to be correlated with some recent sporadic timeout failures:
- https://travis-ci.org/optimizely/javascript-sdk/jobs/397898591
- https://travis-ci.org/optimizely/javascript-sdk/jobs/397898592
- https://travis-ci.org/optimizely/javascript-sdk/jobs/397568472
- https://travis-ci.org/optimizely/javascript-sdk/jobs/397568474
- https://travis-ci.org/optimizely/javascript-sdk/jobs/396745267

This PR `cd`'s the Travis CI pipeline directly into the optimizely-sdk package's dir, and does things there. Doing so seems to reduce the mean CI time (compute time on Travis machines, not wall-clock time) from about 21 mins to 15 mins.

## Test plan
This PR's CI run: [#288](https://travis-ci.org/optimizely/javascript-sdk/builds/397977186).

Author: spencerwilson-optimizely

.travis.yml

@@ -15,12 +15,9 @@ env:
   - secure: WnyM4gMsi2n69O/YZUD/pYwHJXdKDcBv3Hwft2cCw52yYc+z75uuRgdaLKs4BPisckBtnR17dH7hKlPX3HWwjCoqQm1q5qNpbJrArWaEcbotWGF2YFy21ZZ4rKNQmJqdgRj6XFZhLHbncA8v2gQPK7F6GUJ0vsJF/kiTfxAUjefR23oorcKSQrh9BfOxNAYu2Ma92qlaaMmHYbBdlNDM45/EQE+LnPCfboCiJD/5zTYq4Q+XhKLPV01vUDU60pj9ckDNXyLj9X2BwMbAzGAPGE4qTAB/IrMndVsUXblsahtwKQ6yrsUrsdTASz8/3oNkImtY7fqU874jSeG3d7PNBfZs47zkXEVy73ZWNBgM9rzVS5cPaIU3wqpuBoXFntDJcdHQhNTWEYdxmtcTUmxKt5TdUzDhrrkcti2WVLabU3N52aOBeOM0XBpfLkbV+HT6oWi3bNUb+EDMHvCxOxsP4IoEDfFs9HMzNIO3mmC3+2DFbI7s2Mb2oacAut38MbJDYSDTOLL4smG8scA3E0RQO4r8+TNk4aRIMQc7vCKqz7PpbO7Aj9dXSpeHrDmIszSmEoQqmaaGsRBwbXRom2P8fB9FcTbd/wbsfgoFNEPz5DlbtCtCmt0pQMa+3myWveKH52WC5KlFijBSDjYOMUnXbLnj5fK5eKaWp+z6/qcNwU8=
   # BROWSER_STACK_ACCESS_KEY
   - secure: U0GGZw46rJowBtH9gVluIrerB40u2b3uZpH0HsOdLlsXCCaTVk4JXX/JPVPashWAFLC7Enk3UOE4ofeEpVd0wbG6CxtG9/gklc2U2tvkqsdPpFZKaRrXoUzCyyPOmHEC2mXDXctbrncmttM4APaceRfbdTBEZIIfyLJadomjWylA61szFE9IZjvJpiwJO2xa5HI9GVRu3yXJci+riJux+JsDmfJ1hNwv3waMeeg/scddUH0hfgq69ftGs8cpMlYiO20eh32S7uPF7/IJTH1fDJjVKYQZwpypkF6AeI+od5CFTY1ajb25eaBNXThLS0Bo9ZJE/8Sogvon21dEJkt/ClY6R341InbAFXZvz7jyQAisvh0I4zxcu0VUCfh7bEUl6GXMO8VJnyxHEfqB+AIT2RoMXckkhulwiNUsJYH1yJ8mjnLvZq85mWBCp4n4jg0K6Wf46lHpjnHOVpLyLyoFGfiPf90AQVL02AJ3/ia8RkMuj0Ax+AGtiTC/+wy7dsDQOif/VpBNJcx/RciQ24mYOGzAMh4GsUWnXaZ9vXSxliogVNrmIefK5invJ0omv9pIx8NZHTHYGaulh4w6JsliiEq2kH78SlyvSrcsFGTwCY97LLaxiLm/75/Zf+F7LajKC23Fbtnj/LQizitFZqGMJ09DnR52krBAeultqRq8QLM=
-before_script:
-- npm install grunt-cli -g
+before_install: cd packages/optimizely-sdk
 install: npm install
 addons:
   srcclr: true
-script:
-- npm run test-travis
-after_success:
-- npm run coveralls
+script: npm run test-xbrowser
+after_success: npm run coveralls

package.json

@@ -7,7 +7,7 @@
     "clean": "lerna run clean",
     "publish": "lerna publish",
     "test": "lerna run test --stream",
-    "test-travis": "lerna run test-travis --stream"
+    "test-xbrowser": "lerna run test-xbrowser --stream"
   },
   "devDependencies": {
     "lerna": "^2.9.0"

packages/optimizely-sdk/README.md

@@ -65,4 +65,4 @@ The browser bundles also come with a minified / production-ready version.
 
 The .yml of this project contains environment vairables for ```BROWSER_STACK_USERNAME``` and ```BROWSER_STACK_ACCESS_KEY```.
 
-These variables, created in BrowserStack, are encrypted by the TravisCI public key. This is done directly with the TravisCI command line tools; for additional information see travis encrypt-file.
+These variables, created in BrowserStack, are encrypted by the Travis CI public key. This is done directly with the Travis CI command line tools; for additional information see travis encrypt-file.

packages/optimizely-sdk/package.json

@@ -6,7 +6,7 @@
   "browser": "lib/index.browser.js",
   "scripts": {
     "test": "mocha ./lib/*.tests.js ./lib/**/*.tests.js ./lib/**/**/*tests.js --recursive",
-    "test-travis": "npm run test && grunt",
+    "test-xbrowser": "grunt karma",
     "lint": "eslint lib/**",
     "cover": "istanbul cover _mocha ./lib/*.tests.js ./lib/**/*.tests.js ./lib/**/**/*tests.js",
     "coveralls": "npm run cover -- --report lcovonly && cat ./coverage/lcov.info | coveralls",