Move out configuration params from params

[jkaflik]

At the moment everything lies in a single src/openmower/config directory. It should be split into two:

• ROS node & URDF params
• actual configuration

[rovo89]

Are you planning to add some override or extension mechanism? Some parameters will be different between mowers. Some will be different depending on the individual build. For example, I'm using a UM980 connected via USB, so I'll need to change the GPS device and baud rate.

I assume I would have to copy the whole gps.yml and change the values? Or even all the config files?

If on the other hand the user-maintained config files just contained the changed values, it's more easily possible to change defaults and it's clear to see the deviations from the standard.