Reimplement way in which migrations are handled #600
Description
Currently, migrations are run when Manage is first started. That is undesirable, as it doesn't give any control on if and when that are run. It also often results in issues with backward-incompatibility, where a new Manage-release will change the database causing a roll-back to become impossible.
A second issue is that database migrations are not recorded properly. The changes are made in the database, but not recorded in a revision, so they magically appear in whatever the last "real" modification of the entity was. That is most confusing.
So I would like the following:
- migrations should not be run automatically
- they could be run either from the command line by a TPM. or from a new tab onder System in the ui.
- in both cases, the interface should be able to list all migrations and indicate which ones have been run and when
- each migration should record the changes in a proper revision