Hiding media from folder with .nomedia file.

This patch allows media files present in a folder with
a .nomedia file to be hidden after these files have been
previously indexed.

Bug: http://code.google.com/p/android/issues/detail?id=24162



Change-Id: Ia42133d0a7b119c76b5eaaffabd054aa1a739817
Signed-off-by: David Sobreira Marques <dpsmarques@gmail.com>