In mid-transition, `modelFor` accepts both camelCase and underscore naming

With facelift router, `modelFor` maintains backwards compatibility
to return a resolved model on a parent route even in mid-transition.
This PR fixes a bug where only the underscore version of a route name
yielded a value in mid transition.
Fix to support jQuery 1.7
Ember.Control add inline docs
 Ember.Select mark 0 as selected value (bugfix for #2763)
Merge pull request #2856 from tricknotes/fix-to-support-jquery-1.7

Fix to support jQuery 1.7
Merge pull request #2860 from teddyzeenny/ember-control

Ember.Control add inline docs
`control` helper more resilient.

Do not install model observers when `modelPath` is undefined.  An alternative
approach would be to default `modelPath` to "model".

Fix #2268.
Merge pull request #2863 from hjdivad/fix-2268

`control` helper more resilient.
Merge pull request #2858 from chrmod/master

Ember.Select mark 0 as selected value
Merge pull request #2855 from machty/model-for-fix

In mid-transition, `modelFor` accepts both camelCase and underscore naming