Adding support for pending widgets in AutoInstall layout

> Pending widgets whill show a loading progress while the app
is being installed.
> Extra bind options can be defined using the tub tags
    <extra key="key-name" value="key-value" />
  These are sent as widget options when the widget is bound.
> If the widget has any config activity, it is not shown
> Required attributes:
   className, packageName, x, y, spanY, spanY & screen

Bug: 30279609
Change-Id: I1338618bfa5d86967339dffb68c12b1add6eb5d7