[FEATURE ember-metal-is-blank]
Merge pull request #4049 from efigarolam/master

[FEATURE] isBlank method for filtering whitespace strings
[BUGFIX] Create _super when applying mixins. Use __nextSuper in wrappers

This sets _super on the context of all Ember objects, and also sets _super
on mergedProperty contexts if they have a property that is a function.

Fixes #3523, discussed in #3683
[BUGFIX release] Reduce read-only calls to meta
[BUGFIX release] Pass meta into watchKey when possible
[BUGFIX release] Reduce even more meta calls by passing it along in other places
[BUGFIX release] Reduce even more meta calls by passing it along in other places (doh, missed one)
[BUGFIX beta] fixed issue with transition.resolvedModels

Already-resolved parent models weren't showing
up in modelFor hook post-refactor

cc @wagenet
Merge pull request #3683 from mixonic/super

[BUGFIX] Ever-present _super, avoids infinite loop case
[BUGFIX release] finishChains was modifying meta incorrectly
[FEATURE ember-eager-update-url] Eagerly update link-to urls

Previously, the url in the address bar would only update
at the very end up the transition. This change causes the
url update to happen immediately unless the transition
was aborted/redirected within the same run loop, which
provides for a better UX 99% of the time.
Merge pull request #4122 from machty/eager-url-update

[FEATURE ember-eager-update-url] Eagerly update link-to urls
[BUGFIX release] We don't need to call didChange after we've copied
[FEATURE ember-eager-update-url] tweak for hash location

Need to strip hash before eagerly updating url.