Set database collation

Set database collation to match upstream settings. Related to https://github.com/gitlabhq/gitlabhq/pull/8195.
@bbodenmiller I think it is because of the way postgresql works. template0 is default and it sets the collation automatically. The [postgres documentation says](http://www.postgresql.org/docs/9.3/static/sql-createdatabase.html):

```
The encoding and locale settings must match those of the template database, except when template0 is used as template. This is because other databases might contain data that does not match the specified encoding, or might contain indexes whose sort ordering is affected by LC_COLLATE and LC_CTYPE. Copying such data would result in a database that is corrupt according to the new settings. template0, however, is known to not contain any data or indexes that would be affected.
```
The fact we didn't encounter issue with postgresql(that I am aware of) didn't force us to change anything from the defaults.