move image_rotate.cpp to nodelet directory according to the directory convenstion of image_pipeline
make image_rotate nodelet class

Conflicts:
	image_rotate/CMakeLists.txt
	image_rotate/package.xml
	image_rotate/src/nodelet/image_rotate_nodelet.cpp
add executable to load image_rotate/image_rotate nodelet.
add xml file to export nodelet definition.

Conflicts:
	image_rotate/package.xml
use getNodeHandle rather than getPrivateNodeHandle
use NODELET_** macros instead of ROS_** macros