Support 1.x/2.x db upgrades, refs #4494

Apply new database upgrades selectively depending on the milestone.
Small fixes
Simplify code comment
Add fks support in addColumn (QubitMigrate)
Add information_object.source_metadata_id column

I'm adding an extra column to store the source standard
(refs #3891). TODO: add taxonomy and terms. Migration added,
taking this chance to do more migration testing (refs #4494).
Add information object templates taxonomy/terms

Using the new migration scripts (arMigration0094 class, refs #4494),
this commit adds the needed taxonomy and terms regarding to the new
switch template feature based on source standard (refs #3894).
Merge branch 'issue-4494' into 1.x.

Fixes #4494. See the issue page for more details.

New migration scripts are located under:
- lib/task/migrate/migrations/*.class.php
The existing ones can be used as examples.