Add MigrationManager.
Merge branch 'develop' into migrations

Conflicts:
	module/Omeka/config/module.config.php
Add table resolver.
Update install schema to add migration table.
Add column support to table resolver.
Add simple migrate page.
Add task to initially record migrations on install.
Merge branch 'migrations' into develop

Conflicts:
	module/Omeka/config/module.config.php