Revert the license to keep its original

[gaoethan]

Revert the license which was aligned to Apache 2.0 in #216 to keep its original
Signed-off-by: Ethan Gao ethan.gao@linux.intel.com

[gaoethan]

@mikaelarguedas I've already reverted all the license to its original, please kindly help give a simple review and let me if any problem. thanks !

[mikaelarguedas]

This looks good 👍
Thanks @gaoethan for iterating on this.

Note: In general we add new copyright notice when a significant feature / behavioral change is being made. By the look of it, most of the files changes are about style (for example rgb_colors.h) and thus would not qualify to add a new copyright holder.
We can keep it as is for now, but we should keep it in mind in the future.

Piggy-backing on the remark about style changes, please consider (when you have a chance) addressing the remark about keeping the diff minimal with the ROS1 version, by either submitting style changes upstream or not applying them to the ros2 branch

[mikaelarguedas]

lgtm