SqlScript: execute multiple statements one by one

Some drivers [f.e. MySQL Connector] do not like multiple statements
being passed to .execute(). They require either passing multi=True
parameter to .execute() that is not DB-API 2.0 defined, or executing
those statements one by one.

For that patch, I've chosen the second option to stay away from driver
specific hacks.

Also removed SQLite hack that seems to be related to the same multiple
statements issue.

blueprint enable-mysql-connector

Change-Id: Ic6d53ed1fef8aee9471f3540f06b39cd5ee4ef82