Directory restructure and full support for pip install and pip install -e (development mode)

This pull has the following
   1. The directory restructuring and re-organization into 2 sub project directories pyjs-tools and pyjs-pyjamas
   2. Now works with virtualenv python sandboxing.
   3. full support for pip install and pip-install -e (development mode)
   4. Some documentation file changes to describe the new install and development flow
   5. a pip install requirements.txt to keep things simple 

ATTENTION Kees Bos: Can you please check if you examples restructuring is still fine and I have not screwed it up.
That was the one merge conflict I had to deal with, but was relatively simple.