Don't use double quotes in MySQL queries

MySQL databases with the ANSI_QUOTES mode enabled treat " as an identifier
quote (see https://dev.mysql.com/doc/refman/5.7/en/sql-mode.html#sqlmode_ansi_quotes

).
So for such databases the 'occ upgrade' fails with an error message like this:
... unknown column 'oc_*' in where clause.

This fix replaces the doulbe quotes with single quotes that should be always
used in MySQL queries to quote literal strings.

Signed-off-by: Robin Müller <robin.mueller@1und1.de>