[gazebo_ros] Fix for #246

Fixing issue #246 in gzserver.
Merge branch 'indigo-devel' into patch-1
Extended the fix for #246 also to debug, gazebo, gzclient and perf scripts.
Merge pull request #247 from peci1/patch-1

[gazebo_ros] Fix for #246
Merge remote-tracking branch 'upstream/indigo-devel' into indigo-devel
gazebo_ros_diff_drive published now on request a trip_record and the current exceuted command and target command
fixes
ros_diff_drive enhanced with trip counter and command feedback