Allow the use of setup.py develop mode

- Moved python packages to the project top-level folder
- Moved native sources as well, in the top-level "native" folder
- Updated setup.py accordingly
Renamed "test" -> "tests"
Added a warning comment to testsuite.py

File must be executed from the tests folder, not the project top folder
Reformated tests files

... but they have not been corrected nor enhanced
Renamed files to be usable with Nosetests

The JVM is loaded in __init__.py, in method setup_package()
See https://nose.readthedocs.org/en/latest/writing_tests.html
Add configuration file for coverage
Updated paths in MANIFEST.in

src/native -> native