Remove Ember.String.classify from ember-inflector

I think Ember.String.classify should be removed from ember-inflector
since it is provided by Ember.String itself.

I removed all tests as well. I even removed the test
_equal(Ember.String.classify('words'),'Word');_ which I think was
actually an error > it should
_equal(Ember.String.classify('words'),'Words');_.
Revert "Remove Ember.String.classify from ember-inflector"

This reverts commit 4cd5434cfe1a6a3addc9e250be9b5f8b2c2f0461.
Upgrade libraries
Add a flag Ember.INFLECTED_CLASSIFY

Add a flag Ember.INFLECTED_CLASSIFY defaulted to false. If
Ember.INFLECTED_CLASSIFY is true, Ember.String.classify function from
ember-inflector will be used instead of Ember.String.classify function
from ember-runtime.
Merge pull request #4 from karlguillotte/master

Remove Ember.String.classify since it is provided in ember-runtime module