Set up coveralls code coverage reporting

[jslee02]

This pull request adds code coverage testing and reporting the result to coveralls.

[jslee02]

coveralls reported as a failure because I set the coverage threshold for failure to 50.0% at first. It's relaxed to 49.0% so the test should be passed, but the result seems not being updated.

[jslee02]

Can we merge this? Coverage test would be a good tool for managing the code quality.

[mamoll]

Maybe delete this and add lcov and curl to the packages list in travis.yml (assuming that lcov and curl have been whitelisted by Travis CI)? This would allow them to be cached by Travis.

[mamoll]

👍

[davetcoleman]

This is a really cool feature, I'm sure you are too busy @jslee02 but moveit could sure use this coverage feature!

[jslee02]

@davetcoleman Yeah, I found coverage reporting feature is useful so am using this for DART (another my major open source project) as well. It would be straightforward to setup this feature to moveit thanks to coveralls and coveralls-cmake. Please let me know if there something I could help.

[davetcoleman]

i've added this to my moveit todo list, will probably ping you later!