Source Selector: Add different presentation modes and cancel button

* Adds cancel button to source selector
* Can now pass in a jQuery object in options object as 'container'
* If 'container' is a valid jQuery object, source selector will
  be appended to it.
* If no container is passed, the selector will be shown as a dialog.
* If 'top' and 'left' options are passed, dialog will be positioned
  using those settings. If not the dialog will be centered.

Change-Id: Ib605fe3880f3092545aa35fe1ce6950e1fcf8c00
Merge "Source Selector: Add different presentation modes and cancel button"