Added $.text() method

This will set the appropriate text-related attribute based on the view
type. For example, on a Label it will set 'text' but on a Button it will
set 'title'.
Removed backbone-extensions for API consistency

This removes the tagName -> viewName alias in favor of just using
tagName (like Backbone on the web does). With the upcoming XML-based
element creation syntax, tagName makes more conceptual sense. We also
removed the override of the default tagName to 'View'. Now, if a view
has a tagName of 'div' then it is renamed to 'View' before creation.
This is surprisingly helpful when using other libraries, especially Jade
in combination with XML-based element creation (you'll see!).

It also removes the override of _configure that merged attributes passed
in the constuctor. As we move towards a more CSS-like approach for
styling elements this should provide less of a benefit, so I'm removing
it in favor of maintaining consistency with Backbone.

Now the only thing needed to mix titanium-backbone in to Backbone is:

Backbone.$ = require('tb').$
$.append can now append multiple nodes at a time
Added $.html()

While the name may not make sense in the context of Titanium, this
behaves the same was as the jQuery/Zepto version. It replaces the
content of the parent element with the child element(s).
Added documentation for $.text
Added mock Ti.iOS.AdView
Improved console output of ti.createView