Add GitHub actions for linting and source-build CI (#178)

* Use github actions to perform CI

- One source build to test against latest master
- One build on top of nightly image to give quick feedback

Signed-off-by: Mikael Arguedas <mikael.arguedas@gmail.com>

* comment integration tests until fastrtps is fixed

Signed-off-by: Mikael Arguedas <mikael.arguedas@gmail.com>

* comment out end-to-end testing for now

Signed-off-by: Mikael Arguedas <mikael.arguedas@gmail.com>

* add badges to readme

Signed-off-by: Mikael Arguedas <mikael.arguedas@gmail.com>

* use ROS_DISTRO env var

Signed-off-by: Mikael Arguedas <mikael.arguedas@gmail.com>

* test sequentially and print to console

Signed-off-by: Mikael Arguedas <mikael.arguedas@gmail.com>

* run after nightly docker images rebuild

Signed-off-by: Mikael Arguedas <mikael.arguedas@gmail.com>

* add comment about using upstream action-ros-ci

Signed-off-by: Mikael Arguedas <mikael.arguedas@gmail.com>