Change the MySQL collation type to utf8_bin to ensure case-sensitive tags are supported

MySQL tables had a collation type of utf8_ci, which makes the name case-insensitive. Previously this migration was run only after indices were built, but it needs to happen before if there is existing data that is case-sensitive. This is an idempotent change, so applying it again in the existing migration (20150425164651) should not change anything.

This is related to !623 (merged), but this migration should run before that one.

• Closes #1589 (closed)
• Closes https://github.com/gitlabhq/gitlabhq/issues/9255

cc: @vsizov, @JobV

Thanks @stanhu, just what we needed!

Looks good. Let me test it.

We should not use third party classes and models in migrations. I'll fix

Ah it is duplicate. Sorry.

Status changed to merged

mentioned in commit d881345e

mentioned in commit 7880589d