AndroidStorageProvider: Add compatibilty with fuse daemon mounted storage

* Also show all available mounted storage options when selecting 'External Storage' while browsing, instead of /storage/sdcard0/ which getExternalStorage() returns.

Signed-off-by: Brandon McAnsh <brandonm@matricom.net>
Are we sure that this is valid for all android versions we support and for all android devices?

PS: the two lines above each have a whitespace to spare.