Install MySQL libraries on Mac OS X 10.7

This module will install MySQL55 using Macports. Path is exported
using mysql_env.sh.erb

Change-Id: I982851d97d9742964851902d68f689a8c947e596
Reviewed-by: Sergio Ahumada <sergio.ahumada@digia.com>
Reviewed-by: Samuli Piippo <samuli.piippo@digia.com>