A proper home for find_mtimes()

[jodal]

[Moved from PR comment in #10.]

In Mopidy, mopidy.internal.path.find_times() is now a reexport of mopidy.internal.mtimes.find_times(). It is only used by tests/audio/test_scan.py. I think that we should either:

• conclude that the mopidy.internal.mtimes module belongs in Mopidy-Local and not Mopidy, or
• make find_times() a public method, maybe in the mopidy.audio.scan module?

@adamcik Any thoughts on the placement of the scanner and its supporting functions?

[adamcik]

I would err towards moving out. The find time stuff is all done for local's scanner at least, while I think the scanner might be used by e.g. the stream backend? If so we need to keep at least some of it mopidy.