localization ekf zeros pose

[jphaneuf]

Discovered pose info from EKF close to zero.

In robot_localization/src/ros_filter.cpp , function preparePose takes a pose msg and does some transforms based on target and header frames.
It is doing a transform that is not useful to us, resulting in zeros.

Starting at line 2466 is the logic to determine what frame to use (we fall in to the else statement, 'use target frame')

There is a probably an elegant way to fix this. but if you delete that logic or add a line afterwards:
poseTmp.stamp_ = msg->header.stamp;

Then that appears to work, pending testing.