Add default config setup.

Allows specifying configuration in the following files:

* `config/environment.js` - This is loaded in all enviroments.
* `config/environments/production.js` - This is loaded when
  building with `grunt dist`.
* `config/environments/development.js` - This is loaded when
  building a normal development server (via `grunt server` generally).
* `config/environments/test.js` - This is loaded when running tests via
  either browsing to `/tests` URL or running via karma.
Merge pull request #370 from rjackson/add_config

Add default config setup.
Don't destroy global config object

This will encourage people not to destory their window.ENV object by
reassigning it a completely new value.

The environemnt specific files should load after `environemnt.js` has
loaded. This way the values assigned to `window.ENV` in those
environment specific files can overwrite any defaults set in
`environment.js`

I have also cleaned up the comments somewhat and included a simple
example of setting a config value.
Merge pull request #372 from bcardarella/bc-cleaner-default-env-files

Don't destroy global config object
Added example using httpResponse
Merge branch 'master' of https://github.com/taras/ember-app-kit

* 'master' of https://github.com/taras/ember-app-kit:
  Removed unused variable
  Added expressServer to karma:test, karma:ci and karma:browsers tasks Removed proxyMethod argument from server and test:server tasks
  Fixed the test
  Add ic.ajax to .jshintrc
  Moved proxy configuration into karma.js
  Added test for API Stub
  Removed string template from property name because grunt wasn’t replacing the value.
  Fixed wrong variable name after renaming
  Task options are used to configure proxies in Karma
  Changed to accept namespace argument namespace argument is now used to setup the server namespace
  Changed to use new configuration options Cleaned up variable names api.namespace is now being passed to routes.js
  Changed to use new configuration options from package.json
  Changed APIMethod & proxyURL to use prettier configuration names under api hash

Conflicts:
	tests/.jshintrc