Cherry pick oslo-incubator db fixes

The patch cherrypicks 2 fixes related to utf8 migration:

 * Ib5c0f93c788afda92aad862e50dc086dc39605f1: Ignore migrate versioning tables in utf8 sanity check

 * I7f271d846141ac72dde3fb0d12159b125018eb2c: Make table utf-8 charset checking be optional for DB migration

Change-Id: Icb811e846c05f863a42611054f2e3f30a47573db
Closes-Bug: #1301036
Merge "Cherry pick oslo-incubator db fixes"