Run snyk checks on requirements, but only for python 2.7

- snyk needs to check requirements.txt, so add one, but be warned it
  isn't actually used as part of installing this project's dependencies;
  see setup.py
- setup.py needs ipaddress for all python 2.x and python <3.3, but we're
  only testing 3.x for versions 3.3 or greater. Therefore only check 2.7
  since we'd expect the same snyk result for all python 2.x versions.

Author: andyjack

.travis.yml

@@ -23,6 +23,15 @@ before_install:
   - pip install coverage coveralls
   - if [[ $TRAVIS_PYTHON_VERSION == '3.6' ]]; then pip install pylint yapf; fi
   - if [[ $TRAVIS_PYTHON_VERSION == '2.6' ]]; then pip install unittest2; fi
+  - |
+    if [[ $TRAVIS_PYTHON_VERSION == '2.7' ]]; then
+      sudo apt-get install -y nodejs;
+      npm install -g snyk;
+      pip install -r requirements.txt;
+    fi
+
+install:
+  - if [[ $TRAVIS_PYTHON_VERSION == '2.7' ]]; then snyk test --org=maxmind; fi
 
 script:
   - if [[ $TRAVIS_PYTHON_VERSION != 'pypy' ]]; then export MM_FORCE_EXT_TESTS=1; fi
@@ -32,6 +41,7 @@ script:
 
 after_success:
   - coveralls
+  - if [[ $TRAVIS_BRANCH == 'master' && $TRAVIS_PULL_REQUEST == 'false' && $TRAVIS_PYTHON_VERSION == '2.7' ]]; then snyk monitor --org=maxmind --project=maxmind/MaxMind-DB-Reader-python; fi
 
 notifications:
   email:
@@ -42,7 +52,8 @@ notifications:
 
 env:
   global:
-   - secure: "pVcpV/al5Q607TbRzl/sbkdsx5hUjxehaJm6t5tgWrFn45icwdZrPw3JWcpt0R57NhPvXHxcJdm4WBtcGElWoDtR52QOW3yYh+gRw23y1MJg+5qHIbh5R1sOC/fLJ9TzQzvvRH5QQ5bKIe1hRQW9Cpqm7nX5Zhq6SqnAzcG1emE="
+    - secure: "pVcpV/al5Q607TbRzl/sbkdsx5hUjxehaJm6t5tgWrFn45icwdZrPw3JWcpt0R57NhPvXHxcJdm4WBtcGElWoDtR52QOW3yYh+gRw23y1MJg+5qHIbh5R1sOC/fLJ9TzQzvvRH5QQ5bKIe1hRQW9Cpqm7nX5Zhq6SqnAzcG1emE="
+    - secure: "idzTTvCWmC0TYgYxQFOaZju86TUzKLaMKs2ZZsGloklf0mk0d3XH/CD5VYDPgP++/7Kmw9zC401EZyRC6anZYB0qCXwRulgux2Io5HCWChIrZTSx3DoSl+VRVi0cUkfMNomrwduJ0g1vVnDXp6xM8ITE574jwpasUJ2MOvVykdU="
 
 addons:
   coverity_scan:

requirements.txt

@@ -0,0 +1,4 @@
+# NOTE: This project does not use requirements.txt, it uses setup.py.
+# This file is only present to support dependency checks in CI for certain
+# python versions.
+ipaddress