Add a summary of how to submit a pull request

Also add REP 137 reference.
bump version for robot_model
Merge pull request #770 from isucan/master

bump version to robot_model
fixing quotes
Add 2 rqt plugin metapkgs to groovy/source.yaml.
Merge pull request #772 from 130s/master

Add 2 rqt plugin metapkgs to groovy/source.yaml.
add jenkins_job_timeout for devel and doc jobs
rqt_common_plugins) 0.2.16-0 for hydro. Status added.
releasing smach 1.3.0 to hydro
fixing packages list formatting
releasing joystick_drivers 1.9.10 to groovy and hydro
Merge pull request #775 from jbohren-forks/master

releasing smach 1.3.0 to hydro
Merge pull request #768 from ros/readme_update

Add a summary of how to submit a pull request
adding maintainer status
Merge pull request #776 from jbohren-forks/joystick_drivers

releasing joystick_drivers 1.9.10 to groovy and hydro
add more timeouts for groovy and hydro
[hydro] remove version of joystick_drivers since the gbp does not contain a hydro release
re-adding joystick drivers to hydro
Merge pull request #777 from jbohren-forks/joystick_drivers

re-adding joystick drivers to hydro
Merge pull request #774 from 130s/master

rqt_common_plugins) 0.2.16-0 for hydro. Maintenance status added.