extract maintainer emails for notification in devel jobs

Please review and merge.

The devel jobs need to be modified to actually use the information generated by this script (ros-infrastructure/jenkins_tools#22).

Currently the maintainer does not get notified about the result: http://jenkins.ros.org/job/devel-indigo-nodelet_core/ARCH_PARAM=amd64,UBUNTU_PARAM=trusty,label=devel/4/console