[FEATURE] Remove Migration code

Code was migrated to https://github.com/Ecodev/dam2media

Change-Id: I9b25bd0c1fc0f7616991fe3e6d75674dcf06c003
[TASK] Update class description

Change-Id: I79b4c975d6160847f0e66674c58ab9010f78420a
[TASK] Add pointer to the on-line documentation

Change-Id: Id37c3529f30618b9f98dc5ed0a3435be218f38d1