Add migration method to test sqldump files
Add migration method to test sqldump files

This is very useful for testing real migration issues from a mysqldump.
You use it like this:

    def _pre_upgrade_031(self, engine):
       _load_mysql_dump_file(engine, 'dump.sql')

Change-Id: I0d5680d42d608bdc1cb70ccdf19a4c867b372351

ntt-sic/heat,srznew/heat,jasondunsmore/heat,gonzolino/heat,srznew/heat,cryptickp/heat,NeCTAR-RC/heat,cryptickp/heat,pshchelo/heat,pratikmallya/heat,noironetworks/heat,takeshineshiro/heat,openstack/heat,noironetworks/heat,steveb/heat,steveb/heat,maestro-hybrid-cloud/heat,rdo-management/heat,ntt-sic/heat,miguelgrinberg/heat,cwolferh/heat-scratch,miguelgrinberg/heat,dims/heat,pshchelo/heat,gonzolino/heat,dragorosson/heat,NeCTAR-RC/heat,rh-s/heat,maestro-hybrid-cloud/heat,cwolferh/heat-scratch,dims/heat,jasondunsmore/heat,pratikmallya/heat,openstack/heat,dragorosson/heat,rh-s/heat,redhat-openstack/heat,takeshineshiro/heat,rdo-management/heat,redhat-openstack/heat