Implement showing of apk icon and image and video thumbs in listing

Patchset 8: Move some stuff to MimeTypeHelper
            Add cache
            Add image and thumbail support
            Add setting for this (defaul false for improve performance)
Patchset 9: Fixed icon derp display
            Same size for all drawables
Patchset 10: Async drawable load
             Shrink cache
Patchset 11: Use layout's width and height to scale the images
Patchset 12: Music album thumbs
Patchset 13: Added suggestions
             Fixed FC
Patchset 14: Use content observer for icons
             Keep context in icon holder
             Fix scroll position being reset on thumbnail load
Patchset 15: Additional fixes and optimizations
Patchset 16: Do not saturate the ui with constants redrawing
             Do not send back events while changing to a new directory
             Fix FC on HistoryActivity (creation of a ContentObserver inside of a non-ui thread)
             Added normalized media paths
Patchset 17: Use a HandlerThread to handle the preview loads
Patchset 18: Optimizations
Patchset 19: Fix deadlock
Patchset 20: Remove debug leftover
Patchset 21: Fix whitespace
Patchset 22: Misc. cleanup

Change-Id: I0a4ea801ff0cfbf31dda125b8925e7d35f4c3c99
Some optimizations spotted during profiling.

Change-Id: Ice5cc24d2574894798370eaaae144713414eb6cf