Add a check for jQuery versions with a specific checkbox click bug.
Fire mousedown & mouseup on clicks, plus focus for text fields.
Quoteless route param in linkTo performs lookup

See: http://discuss.emberjs.com/t/upcoming-linkto-changes-ideas/1635

New behavior is wrapped in ENV.HELPER_PARAM_LOOKUPS flag,
named that way since the behavior will likely be applied to
actions as well.

The routeName param is bound. Saving bound contexts for a later PR
for now (potentially complicated).
Merge pull request #2905 from machty/string-link-to

Quoteless route param in linkTo performs lookup
Use Ember.isNone instead of Ember.none
Merge pull request #2912 from mhelabs/use-is-none

Use Ember.isNone instead of Ember.none
Merge pull request #2906 from eventualbuddha/make-ember-testing-click-more-robust

Make ember-testing click() more robust