[FEATURE ember-runtime-sortBy] Adds `sortBy` to the Enumerable mixin.

'sortBy' allows for sorting an enumerable by one the values of one or
more properties.

@kselden / @lukemelia
[String-humanize] Add Ember.String.humanize
replaceWith/replaceRoute documentation

Updated the documentation to explain the difference between replaceWith
and transitionTo as well as replaceRoute and transitionToRoute.  I also
added documentation explaining how multiple models are used when they
are sent to those 4 methods.
[Improved assert for #3457] provide helpful assertion if needs is specified but no container is present.
Merge pull request #3456 from kingpin2k/replaceDocumentation

replaceWith/replaceRoute documentation
typo in documentation
Merge pull request #3459 from kingpin2k/typo

typo in documentation
Merge pull request #3224 from sentientmonkey/master

Add Ember.String.humanize
fix initializer assertion messages

(@stefanpenner / @rjackson)
Merge pull request #3464 from rjackson/improve-assertions

fix initializer assertion messages
Merge pull request #3458 from stefanpenner/improved_needs_assertion

[Improved assert for #3457] provide helpful assertion if needs is specified but no container is present.
Merge pull request #3446 from lukemelia/sort-by

[FEATURE ember-runtime-sortBy] Adds `sortBy` to the Enumerable mixin.