Fix rosdeps for Noetic, CMake cleanup, add CI

[brentyi]

I've been trying to get blue_core to build in 20.04; the main things blocking this have been dependency-related:

• No release of serial for Noetic (Noetic Release wjwwood/serial#222)
• orocos_kdl keys have been removed (Add rosdep rules for orocos kdl and orocos bfl ros/rosdistro#23841)

Building from source works fine for fixing the first point; this PR fixes the second by pointing the orocos dependency at apt.

Should just magically work in Kinetic/Melodic, but would appreciate if someone could check!

[wuphilipp]

Looks good, I tested the README instructions on freshly cloned blue_core repos in kinetic and melodic, so hopefully, that's good enough verification.

we should probably try to get some CI running for the code base

[wuphilipp]

Also should we update the README to note noetic support?

[gbalke]

I was going to offer to check on both but it seems like Philipp's a step ahead. Feel free to PR after addressing his comments.

[brentyi]

Also should we update the README to note noetic support?

Gonna hold off on this because:

• serial package still needs to be built from source
• All of the Python bits will run in Python3 on Noetic; this is not thoroughly tested

[wuphilipp]

Also should we update the README to note noetic support?

Gonna hold off on this because:

• serial package still needs to be built from source
• All of the Python bits will run in Python3 on Noetic; this is not thoroughly tested

Sounds good!