CM11 Themes: Ensure customTheme is not null.

The configuration retrieved via getConfiguration() sometimes contains
a null customTheme which results in the theme returning to holo when
applying a component such as icons.  Icons will change but styles
and fonts would return to the default.

Change-Id: Iac0cb8eed5de8fdc9fe8efd697d968f26e801c08
CM11 Themes: Properly handle SystemUI theme package name.

Change-Id: Ia8915684e1620184dcc513c2c5039ea20aabbd04
CM11 Themes: Include alarms in mixnmatch.

Change-Id: I004f6b0149d71c8ed1a3952704f5a3521eca5add
CM11 Themes: Common overlay for sharing resources. [1/2]

This patch will allow themes to contain common resources
which can be shared by all overlays.

Common resources will reside in assets/overlays/common and
can be referenced by other overlays.

Common resources will be referenced using the common package
name, i.e. To reference the common drawable some_drawable for
com.example.theme the theme designer would use
"@*common:drawable/some_drawable"

Change-Id: I395b6bd5eae91b00265a8e9221856ef7bf5d115a