1. Created interface classes for reading video streams
(in imagereaders.py)
2. Created a class for ball detection (for reusability)
3. Reworked colorpicker, now it is possible to choose the mode of
operation from command line (available are live from Nao, from
video file or from webcam). It is possible to capture only the
first image of a stream and work on it. Colorpicker now can save
the settings on exit or load settings on startup.
Sourcing .bashrc from install_ros.sh didn't have any effect, since
.bashrc needs to be sourced from an interactive shell. Because of this,
it was required to restart the terminal for ROS to work. Now, the ROS
startup scripts are sourced directly from the installation script,
thus eliminating the need to restart the terminal.
Added instructions to README to check the installation success.
