Improved the fallback logic parsing track number and title from file name
Improved the fallback logic parsing track number and title from file name

- Fixed the following oddities from the fallback logic of parsing the track number and title from file name in absense of the corresponding metadata tags:
   1. The track number could be parsed from file name only if there was no track title in metadata.
   2. The file extension got included in the tract title if there wasn't a track number present in the file name.
   3. File extensions other than .mp3, .ogg, and .flac got included in the track title. The Music app can index and play many others like .wav, .mp4, and .m4b.
- Closes #261

owncloud/music,paulijar/music,owncloud/music,paulijar/music,paulijar/music,Faldon/music,paulijar/music,Faldon/music,Faldon/music,Faldon/music,owncloud/music,Faldon/music,paulijar/music,owncloud/music,owncloud/music