If extra init_command options are given for the Django connector, load them

[svdgraaf]

This adds support for the init_command option, which is used in other mysql connectors (and in the Django Database config setting).

In the _post_connection method, it now calls the _execute_query to run the given sql commands in init_command.

Adding this option inside the Django database config now works, previously this was ignored.

{
    "default": {
        "ENGINE": "mysql.connector.django",
        "NAME": DBCONFIG["database"],
        "USER": "user",
        "PASSWORD": "password",
        "HOST": DBCONFIG["host"],
        "PORT": DBCONFIG["port"],
        "OPTIONS": {
            "init_command": "SET foo='bar';"
        }
    }
}

I've added a test for the Django connector, but I had a hard time getting all tests for the other parts to work locally. Things "should be fine though (tm)", but that's probably not good enough :D Any pointers to where I should implement the unit tests are welcome.

Any comments or feedback in general is much appreciated.

I've filled out and signed the OCA.
I confirm the code being submitted is offered under the terms of the OCA, and that I am authorized to contribute it.

[mysql-oca-bot]

Hi, thank you for your contribution. Your code has been assigned to an internal queue. Please follow
bug http://bugs.mysql.com/bug.php?id=108076 for updates.
Thanks