adds child_frame_id to odom msg
adds base_frame_id param (defaults to base_link)
Merge pull request #38 from efernandez/odom_msg_child_frame_id

Add child_frame_id to odom msg
checks for NaN left/right position to ignore them
adds NaN test
Merge branch 'efernandez/check_nan_position' of https://github.com/efernandez/ros_controllers into efernandez/check_nan_position

Conflicts:
	diff_drive_controller/src/diff_drive_controller.cpp