chore(testing): Testacular config files + rake tasks

- adds testacular config files for jqlite, jquery, modules and e2e tests
- replaces obsolete JsTD Rake tasks with Testacular onces
- rake tasks are parameterazied so that they can be used locally as well as on CI server

usage:

rake test  # run all tests on Chrome
rake test[Safari+Chrome+Opera]  # run all tests on Safari, Chrome and Opera
rake test[Safari]  # run all tests on Safari
rake test:jqlite # run unit tests using jqlite on Chrome
rake test:jqlite[Safari,"--reporter=dots"]  # run jqlite-based unit tests on Safari with dots reporter
rake autotest:jquery  # start testacular with jquery-based config and watch fs for changes
rake test:e2e # run end to end tests
docs(contribute): update misc/contribute docs with Testacular info
chore(): remove unused files
docs(contribute): update contribute docs
chore(Rakefile): fix test:jquery task
docs(README): update README.md with new rake tasks
docs: load angular from CDN only on production

So that when running the docs locally, eg. during e2e testing, we use the latest build version of angular, rather than the stable one from CDN.

This fixes e2e tests running with Testacular.
fix($compile): reference local in isolate scope

This was really corner case:
Watcher needs to return changed value, to notify that model might have changed and one more $digest cycle needs to be performed.

The watcher, that takes care of reference binding into an isolate scope ("="), did not return changed value, if the change was from the isolate scope to the parent.

If any other watcher returned change, it worked fine, as this change caused re-digest.

Closes #1272
chore: add travis config
docs(downloading): update the downloading docs
fix(doc): disable directory listing in docs.angularjs.org
chore(Rakefile): use exec for webserver

exec unlike system replaces the current process. this way when we kill
the webserver process we don't get scary looking 'rake aborted' error
chore(Rakefile): misc_options should support + -> , conversion
chore(test): add junit config for testacular
chore(Rakefile): paralelize closure compilation

this speeds up the build by paralelizing closure compilation (the slowest
piece of the build process)

before:

real  0m14.372s
user  0m31.649s
sys   0m1.006s

after:

real  0m8.191s
user  0m40.473s
sys   0m1.378s
chore(Rakefile): tune JVM for closure compiler

Using the client VM and forcing 32bit mode gives us huge perf boost.

before:

reali   0m8.173s
user    0m39.984s
sys     0m1.408s

after:

real    0m3.000s
user    0m12.687s
sys     0m0.852s
chore(Rakefile): remove test_out dir when cleaning
docs(tutorial): replace JsTD with Testacular + drop snapshots

JsTD references have been replaced with Testacular stuff.

snapshots are PITA to maintain so I'm dropping them, everyone loves the Git
version anyway.
chore(jstd): remove JsTestDriver from our repo

Testacular FTW!
chore(jasmine): remove Jasmine from our repo

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