Propose to update roswww as webserver without ros_comm dependency

[jihoonl]

I was looking into roswww implementation to utilise as webserver which does not bring any ros_comm related dependencies.

The following was requiring ros dependency in roswww

• Logger(rospy.loginfo,logwarn...)
• rosparam for port parameterization
• rospack shell command
• tornado

I would like to propose changes to keep ROS dependency minimal in roswww

• Logger - It would not necessary to ros logger since it is webserver. Rather to use stdio or python logger
• rosparam - replaceable with command line argument.
• rospack shell command - It is necessary. rospack dependency should not be a problem. It is pure C++ module which does not bring ros_comm
• tornado - I have proposed to separated out tornado from rosbridge_server. separate tornado and backports from rosbridge_server RobotWebTools/rosbridge_suite#147

Then roswww package will only depend on

• rosbridge_tools : for tornado
• rospack : for package crawl script

[jihoonl]

RobotWebTools/rosbridge_suite#157 is related.