IMU Topic Connection

[masshu0504]

Currently the imu plugin does not connect properly causing issues with simulation.

[zbrotherton]

More specifically, the gazebo posts imu info to imu_plugin/out when RTAB expects the imu on rtabmap/imu
Obviously, the easy fix is just change where gazebo is posting imu
But it's more realistic to the robot to create a remap rule instead

[zbrotherton]

Not an issue anymore, wontfix