Update schema.xml - add md5_hash column to cover_art table
CoverArtDAO - add method to save cover with md5 hash + getCoverIdFromMd5()
CoverArtCache - starts saving md5 hash in DB (needs more work)
- we could use the md5 hash as the key cache and remove the qhash which stores the md5 hashes
Fixing bug in schema.xml - missing comma
CoverArtDAOTEST - testing saveCoverArt() instead of saveCoverLocation()
CoverDao - Removing unused saveCoverLocation() and getCoverId(coverLoc) + updates tests
- md5Hash is a essential information - we must save loc and md5 in any case
- renaming getCoverIdFromMd5(md5) to getCoverId(md5)
CoverDao::CoverInfo - add md5Hash to coverDao and CoverDaoTest