Your comments

I think you should not say "it will not work, stop trying" if it is not true.. ^^
Maybe we try to find out what kind of problem the OP is facing before we say it doesn't work ;)

As I said before, I have it working right now without any problems.
Just install mariadb from the official repos and remember to install ajenti-v-mysql.
Please have a look at the answer I posted in this thread.

Edit: You then would add a nginx redirect in the created default host to redirect to the main domain.
If you are using ajenti-v, you could try if it is sufficient to edit the config and let ajenti apply it.
For more information about controlling ajenti-v via command line, please have a look here.
I think the command ajenti-ipc v apply should be enough, because you will have edited the config in before..
MariaDB is supported for sure, running an up to date version on my server right now..
What does the plugin section show for the MySQL plugin? It should look like this:

If I understand you right, you want to have every domain which is not specified elsewhere, to be served by an default domain. To do this, you have to check the "Default" box in your port definition section of the website you want to make default.

Additional Info: The "[::]" part is for IPv6.
I don't know why, but the IP-Adress belongs to (at least) this domain:
Problem was solved. Process name must not contain spaces. I have updated my comment above with additional information.
Important Information for all people who want to use my script:
1. Here is an updated version on github:
2. The process name you have to add in ajenti must not contain spaces. The best name for example is "ftpusers"..
Maybe we should not chat here in the comments.. Do you have a google account, so that we can write by hangouts?