Allow for not rendering on navigator

Hi,

First of all thanks for the plug-in, it has help a lot to integrate my recently backbone application with jqm. During development and setting things up I faced with the problem described below when using the [backbone-boilerplate](http://backboneboilerplate.com/) code where the layout view is rendered first and then the other views composing the page. Hope this could be useful.

When rendering the views partially like in composites views,
rendering on navigator has not much meaning, since the view get
rendered part by part in different moments in time. It is better to
leave that task to external users.

Changes:
    Add configuration option to conditionally render view on navigator


Thanks again
David