Update Ember.TextArea and Ember.TextField documentation

text_area.js:
 * update @extends documentation from `Ember.View``` to `Ember.Component`
 * reference `handlebars.helpers.textarea`

text_field.js:
 * update @extends documentation from `Ember.View` to `Ember.Component`
 * reference `handlebars.helpers.input``

controls.js
 * add note for Ember.TextArea and Ember.TextField extending from Ember.Component
 * add references to Ember.Component; warning about not inheriting parent view controller
Merge pull request #3341 from sherwinyu/update-textarea-textfield-documentation

Update textarea textfield documentation