Removes immutable.js references

There doesn't seem to be a very good way to use this with TypeScript at the moment :(

Author: alexgorbatchev

package.json

@@ -66,7 +66,6 @@
   "dependencies": {
     "es6-promise": "^3.1.2",
     "history": "^2.1.1",
-    "immutable": "^3.8.1",
     "isomorphic-fetch": "^2.2.1",
     "lodash": "^4.11.2",
     "normalizr": "^2.0.1",

webpack/config-vendor.ts

@@ -12,7 +12,6 @@ export default config;
 
 config.entry.vendor = [
   'es6-promise',
-  'immutable',
   'history',
   'object.assign',
   'radium',