STYLE: Removed legacy python importing

The preferred way to use itk with python is : import itk
The old way : from Insighttoolkit import *
I removed the old code which is no more needed.

See also : http://itk-users.7.n7.nabble.com/ITK-python-examples-td32400.html
STYLE: Pep8 cleanup for the python files

I cleaned up all the python files (they pass now the pep8 test)

Tool used to check pep8 :
- pip install pep8
- cd to Wrapping/Generators/Python
- pep8 . (to check all files)

Tool to automatically clean up the code :
- pip install autopep8
- autopep8 --in-place --aggressive --aggressive <filename>

Each file was manually checked after the autopep8 changes and manual adjustments were done when needed (the autopep8 tool helped a lot)

Additional changes :
- itkdata.py was renamed as itkData.py
- itktesting.py was renamed as itkTesting.py
- Some files had missing licence headers, I added them
- WrappingCoverage.py : removed python 2.3 compatibility stuff

There is still some deprecated stuff and unused variables to be removed, and more cleanup to be done
(the pyflakes and pylint tools are triggering a lot of warnings)
I did not run the tests (I think there will be some work to get them running).

So this is just a first step, it's not perfect but should allow to work through the code to keep it up to date with the newest python standards.

Change-Id: Ie244c57e00e2ad58050ca2a7f2e880aff6470bc2
Merge topic 'remove-oldstyle-python-module'

399ee428 STYLE: Removed legacy python importing
Merge topic 'pep8-cleanup'

00fff70a STYLE: Pep8 cleanup for the python files