Disable media sync on Android <=2.2 if non-ascii file name found

Unicode normalization is not supported on Android 2.2 and below. Since the new media sync protocol requires file names to be normalized in NFC form, we now abandon a media sync if we detect a media file name that cannot be entirely represented in the ASCII encoding and disable media syncing on that device.

This approach is likely to allow a number of users on those devices to still be able to sync media without issue.

Note: A dialog is shown if media becomes disabled after a sync. Collection syncing is unaffected.
Assume we are on FAT32 for every sync attempt

Temporary measure until we can find a reliable way to detect the file system type.
Merge pull request #441 from hssm/media-sync-protocol

Media sync protocol