rtt_rosparam: New implementation with sane vector support and better control over namespace resolution

This PR is for review purposes, this implementation still requires testing and might require some safety checks / error catching. This aims to provide support for features requested in #5 

See readme for more information: https://github.com/jhu-lcsr-forks/rtt_ros_integration/blob/new-rtt-rosparam/rtt_rosparam/README.md