Support MySQL pre-5.6.1 in the setup script
Support MySQL pre-5.6.1 in the setup script

The `TO_BASE64()` function was only added in MySQL 5.6.1. This changes the way siteadmin password is generated.
On older versions of MySQL, uppercase-only password will be generated. On 5.6.1 and above, it will be mixed-case as previously.

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