Removed inclusion of history.h when using editline

ocl fails on OS X Maverics 10.9 with the following error:

ros_base_ws/src/ocl/taskbrowser/TaskBrowser.cpp:102:12: fatal error: 'editline/history.h' file not found
#include < editline/history.h >

This change allows compilation to succeed.

Does editline distribute a history.h on any other platform?