Turned ball.py into class to make development easier.

Class BallFinder now only does the vision processing, meaning that the algorithm
can be used on board the BBB and for development with a monitor.

A helper function is used to call the class and plot it on screen when used from the command line.
Much neater implementation.
Take colour argument to track both red and blue.
Tcpserver.py skeleton adapted to call classes to do the vision processing.
Example of task switching between threads added.
Merge new tcp code with ball.py updates.
added ball and goal files to tcpserver
added calculations of distance from pixels
edited tcp, arbi test and goal python
return x,y,angle of goal, code cleaned
added a try-except for the cv2.videoCapture
changed video port index to = 1
added a 10ms delay before retrying camera intialise
put visual feedback inside a try-except so it doesn't fail