Merge pull request #392 from marcj/master

Fixed issue that came from the merge of the last 4 PRs.
removed un-used property blobFlag
Merge pull request #394 from staabm/blobflag

removed un-used property blobFlag
Added ObjectCollection::toKeyIndex($keyColumn).
Fixed table/column renaming bug in migration process.

If the migration process decides to rename a table or a column it needs to make sure that it does not rename multiple tables or columns to the same name. Thus I've implemented a `$renamed` array that tracks each renaming so we don't have a duplicated renaming.