[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.
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