Migrates the Angular project from Rake to Grunt.

Benefits:
- Drops Ruby dependency
- Lowers barrier to entry for contributions from JavaScript ninjas
- Simplifies the Angular project setup and build process
- Adopts industry-standard tools specific to JavaScript projects
- Support building angular.js on Windows platform (really?!? why?!?)

BREAKING CHANGE: Rake is completely replaced by Grunt. Below are the deprecated Rake tasks and their Grunt equivalents:

rake --> grunt
rake package --> grunt package
rake init --> N/A
rake clean --> grunt clean
rake concat_scenario --> grunt build:scenario
rake concat --> grunt build
rake concat_scenario --> grunt build:scenario
rake minify --> grunt minify
rake version --> grunt write:version
rake docs --> grunt docs
rake webserver --> grunt webserver
rake test --> grunt test
rake test:unit --> grunt test:unit
rake test:<jqlite|jquery|modules|e2e> --> grunt test:<jqlite|jquery|modules|end2end|e2e>
rake test[Firefox+Safari] --> grunt test --browsers Firefox,Safari
rake test[Safari] --> grunt test --browsers Safari
rake autotest --> grunt autotest

NOTES:
* For convenience grunt test:e2e starts a webserver for you, while grunt test:end2end doesn't.
  Use grunt test:end2end if you already have the webserver running.
* Removes duplicate entry for Describe.js in the angularScenario section of angularFiles.js
* Updates docs/src/gen-docs.js to use #done intead of the deprecated #end
* Uses grunt-contrib-connect instead of lib/nodeserver (removed)
* Removes nodeserver.sh, travis now uses grunt webserver
* Built and minified files are identical to Rake's output, with the exception of one less
  character for git revisions (using --short) and a couple minor whitespace differences

Closes #199

Conflicts:

	Rakefile

it's bundled with Testacular, so we don't need it here

Testacular FTW!

Short summary: if you use local node server everything should work as before,
if you use GAE, everything should work now as well, but we pull assets from CDN.

- GAE doesn't support ':' in filenames, so I had to replace it with '_'
  but only in the filename, all servers were reconfigured to rewrite the
  urls from : to _ when doing file lookup
- We now pull angular assets from google CDN when deployed on GAE (locally
  or in production). When running on a non GAE server we pull assets from
  ../ directory as before
- Since only certain versions of Angular are available on CDN and we want
  to be able to autodeploy docs, I had to pin down the Angular files
  to a "stable" version when running on GAE