Added Optional MySql SSL Certificate

[ArryaLove]

I added a new parameter to the db_inc files called db_cert that references a path to a certificate file that will be used to do TLS security for the MySql server. I then also added the PDO::MYSQL_ATTR_SSL_CA option to all of the db_connect files to use this parameter.

[razvancrainea]

@Jehran thanks for your contribution, it is really appreciated!
In 359fe54 I have approached a more generic, mechanism, where you can define your own attrs, which translate to options. Using this, you can define your own PDO::MYSQL_ATTR_SSL_CA attribute, as well as others. Is this enough for you? If so, we can close this PR.