Refactor to use ScienceStacks/Common

[joseph-hellerstein]

Have created and tested the repo ScienceStacks/Common
Included it as a submodule in SciSheets

Need to have Common codes available in the PYTHONPATH and change in the imports

[joseph-hellerstein]

Approach to path:

1. Move submodule to top level within SciSheets folder
2. Add a path to settings that finds the submodule within the BASEDIR

[joseph-hellerstein]

column.py uses common codes.
To do:

1. Add other paths in settings
2. Import settings whenever use common codes
3. Change imports in codes