Fix license header in some files.
Move from postfix to prefix increment in loops.

Detected by cppcheck 'postfixOperator' warning.
Make position joint limits handle opn loop.

- Lowers the entry barrier for simple robots without velocity measurements,
  poor control tracking or with a slow update rate.
Restore controller stop+unload on node kill.

- Fixes #111.
Minor documentation precision.
Check controller_manager API early. Fast shutdown.

- Check for all services required by spawner at the beginning, so it can know
  early on that it has all its requisites.

- Remove service waiting from shutdown to ensure a fast teardown.
  Usecase: A spawner that dies after the controller manager should not wait
  for services to appear as they will never appear, the controllers are already
  stopped. This happens for example when killing a Gazebo session.
Fix broken unspawner script.
Merge pull request #121 from pal-robotics/hydro-devel

Fixes for next minor release