Add some logcat logs for ugprade process
Ensure correct offsets of upgradeTo/downgradeTo definitions
Workaround for cobertura plugin issues
Do not allow multiple upgrades for the same revision
Extract constant
Add basic tests for release markers
Move some stuff to test utilities
Better tests for fetching current revision number
Do not allow upgradeTo(0, ...)
Enforce non-ascending revision numbers of releases
Enfore correct offset range for downgrades and upgrades between two releases
Enfore upgrade offset greater than 0
Enforce non-negative downgrade offset