Themes: Handle processing themes in separate thread

If themes are being processed and the user attempts to apply a theme
they will be forced to wait for themes to finish processing before
the theme is applied.  This patch moves processing of theme resources
into a separate handler/thread.

Change-Id: Ib30a1be75915364c2867df04d63700be63c9f2c5
core: Fix SMS capitalization

Change-Id: Iab3d935b9980bb802baaf1ebe255ec5cdfa5cee7