Allow for SQLiteCacheDb to be stopped an initialized again.
So we can move away a non-upgradable DB dir out of the way and initialize a clean
one during the database upgrade procedure.
Move the database dir away and start with a fresh one when the upgrade procedure fails.
Show an error dialog when the upgrade procedure failed and the database got
stashed away.
A few fixes/cleanups for the upgrade dialog
Merge pull request #3 from whirm/tftp_plusmetadata_removeswift

Some updates for the new upgrade procedure