Gallery2: fix FC when try to open video folder as MMS attachment.

If there are too many videos in the folder, it will takes some
time to check if all the items are videos, then the application
may not responding.

If it is get content from other apps, it do not display option
menu, no need to check all items.

CRs-Fixed: 581769

Change-Id: Ie59830c8756e3a2ece7fcaa526d8f09212b20d6f
Gallery2: Make picture in selected status when back from homepage

When selected picture and go to homepage,the Gallery will leave
selection mode, so when back to the gallery ,the picture become
unselected status.

Do not leave selection mode when exit the gallery page.

CRs-Fixed: 630782

Change-Id: I8090c65ba39be28f9914735ee96b781068cfa3cf