catkin_make* should allow for MAKEFLAGS

[wjwwood]

Currently caktin_make* programs always give job arguments to make, even if none are passed to them directly, e.g. catkin_make -> make -j8 -l8 and catkin_make -j1 -> make -j1 -l1.

This prevents the Make environment variable MAKEFLAGS from working with catkin_make*. I propose a new logic for handling -j, --jobs, -l, --load-average arguments:

This will allow users to override the make job options with direct arguments to catkin_make*, MAKEFLAGS, or ROS_PARALLEL_JOBS.

EDIT: Removed references to CATKIN_PARALLEL_JOBS because it is overshadowed by MAKEFLAGS and direct arguments, and I did not want it to have the same weird specification as ROS_PARALLEL_JOBS where it has flags for make not just a number.

[wjwwood]

@dirk-thomas for review

[wjwwood]

Scratch that I screwed it up...

[wjwwood]

See: #402