Making SongsOpenHelper into SongsDBHelper singleton
Prevent reader/writer database clashing
Load the filters in a single pane view
When inserting new data, ignore conflicts instead of replacing data (otherwise song _id's change, causing extra songkeywordmap entries)
Close up some leaked Cursor's and Database's

Change-Id: I9253af969453e41b4bf1a91637d15cb926f63219