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. full support for pip install and pip-install -e (development mode)
   3. Some documentation file changes to describe the new install and development flow
   4. a pip install requirements.txt to keep things simple