Gallery2: support live streaming and bookmarks

Users can input a URL for streaming display.
URL bookmarking is supported.

Change-Id: Ia69497cdcfee963ba2209119a5b9dc82b64497da
Gallery2: add some video features

(cherry picked files from commit id
990c6d43ea7c184846e19d41bef0d93aee4e581b)

Change-Id: Ifdcc4e9ab14d1f8b273faa97f0f66ba2f4034bea