Remove deprecated action lookup as methods on controller.

The older lookup in the root of the controller has been deprecated
since late-2013, and is a frequent cause of annoyance for newcomers.
This PR removes the deprecated lookup completely.

This has been discussed with the full core team.
Pass index into computed array callbacks
Merge pull request #5347 from rwjblue/remove-deprecated-controller-action-support

Remove deprecated action lookup as methods on controller.
Unify observer/observes implementation

This is similar to the implementation of FunctionPrototype.property /
Ember.computed.  Now when the Ember.observer function is modified the
function prototype will already of the correct behavior.
Merge pull request #4821 from rondale-sc/unify_observer_observes_implementation

Unify observer/observes implementation
Cache length in observesBefore for loop
Use one variable assignment per declaration.
[FEATURE ember-handlebars-compiler-ast-to-precompile] Allow precompile to accept an already existing Handlebars AST

[FEATURE pass-ast-to-precompile] Adding feature flags

[FEATURE pass-ast-to-precompile] Changing flag name
[BUGFIX] fillIn helper should take context into consideration
Merge pull request #5352 from teddyzeenny/fix-fillin

[BUGFIX] fillIn helper should take context into consideration
Merge pull request #5341 from chadhietala/pass-ast

[FEATURE pass-ast-to-precompile] Allow precompile to accept AST
Merge pull request #5350 from cibernox/fix_cache_length

Cache length in observesBefore for loop
Add missing tests for Ember.DAG

I am not sure sure hoy to tag fixing the absence of tests.
Merge pull request #5354 from cibernox/test_ember_dag

Add missing tests for Ember.DAG
Merge pull request #5351 from rwjblue/single-line-var-declarations

Use one variable assignment per declaration.
Ensure that variable assigning declarations are single line
Merge pull request #5355 from rwjblue/metal-single-line-assigning-declarations

Ensure that variable assigning declarations are single line
ember-runtime single var assignment per declaration

I am working through a code style cleanup effort using
[jscs](https://github.com/mdevils/node-jscs) rules.

You can see the script and rules in:
https://github.com/rwjblue/ember.js/compare/code-style-rules
Merge pull request #5356 from rwjblue/single-line-var-runtime

ember-runtime single var assignment per declaration
ember-application single var assignment per declaration