Original ardrone_brown from: http://brown-ros-pkg.googlecode.com/svn/trunk/experimental/ardrone_brown [revision 2797]
initial commit
Merge branch 'master' of github.com:AutonomyLab/ardrone_brown_mod
My first phase of changes to:

1) Solved CMakeList.txt problem with SDL library
2) Commented out the line of the code that was nagging about unknown tagdata
3) Added the service for turning navdata_demo on/off
4) Sending critical configuration some time after init.
Fix the invalid argument exit of the main SDK to make the driver compatible with roslaunch.
Minor modification in .gitignore
Add `mkdir lib` to build_sdk.sh
fixed small bug in prev commit.
Added remove lib directory and re-create it again to build_sdk to do a clean clean build
Make default camera and navdata states consistent during init.
Added new ROS service to directly set the camera channel.
Setting navdata_demo to off by default so all the data is being sent by Drone.
Acceleration data is now being published to navdata as well.
Made the navdata_demo and cam_state global variables.
Added two new extended topics for front/bottom cameras. the image_raw topic is still the same as before, however the two new extended topics are publishing the cropped version of image_raw seperately for each camera based on cam_state. This feature is incomplete and not well tested.
Support for all camera modes have been added and tested.
Developing tag detection feature, not complete, not tested.
The tag detection works in some conditions, still needs more testing.
Modified Navdata to include tag detection. Tag detection data is pre-configured to detect 2D yellow/orange tags on horizontal camera and Rounderl tags on Vertical camera. TODO: Scaling, Services to change configurations
Some fixes for tag detection.