Don't assume any ringtone is present on external storage.

If that assumption doesn't hold true, the user will lose his ringtone
and won't know why.

Change-Id: I89409e1351792d020c5458f5104f4bb9f2a040f2
Merge "Don't assume any ringtone is present on external storage." into cm-10.1
Merge branch 'cm-10.1' into martincz