Folders: Merge Folders

This allows a folder A's contents to be merged into folder B
when folder A is drag/dropped onto folder B.

Change-Id: I41d62d04b6b4f0932cc68fb6d2a3be111b063d53
Merge branch 'cm-11.0' of https://github.com/CyanogenMod/android_packages_apps_Trebuchet into cm-11.0