Configure mti device on startup

[baronep]

Major Issue Wanted to avoid having to complete the extra step of running mtdevice.py when bringing up a new device

Improvements

• Added optional device configuration to mtnode.py
• Created a sample launch file and yaml config file
• Modified readme to use the launch file instead of launching node seperately
• Added a parameter to support switching between ROS and system timestamps in sensor messages
• Changed log level to INFO to print out the loaded parameter values to make errors which occur by mismatching parameter namespaces more apparent

Testing Tested with Mti-20 and Mti-30

[arunvydhya]

Thanks @baronep for the improvements.
We are doing checks with other MTi devices before we accept the changes.