Fix version of esdocs to work on build agents

Build agents have an old node version installed v4.2.6 and it did not work
with newest 0.5.2 version of esdoc.

This commit makes esdoc version fixed (removes '^') and changes it to the
most up-to-date 0.4.x.

Author: lutovich

package.json

@@ -27,8 +27,8 @@
     "babel-register": "^6.18.0",
     "babelify": "^7.3.0",
     "browserify": "^13.1.0",
-    "esdoc": "^0.5.2",
-    "esdoc-importpath-plugin": "^0.1.1",
+    "esdoc": "0.4.8",
+    "esdoc-importpath-plugin": "0.1.1",
     "fs-extra": "^1.0.0",
     "glob": "^5.0.14",
     "gulp": "^3.9.1",