B3j0f-conf

------------------

- fix bug about targets parameter.
- update README in fixing the example.

------------------

- use the docs directory related to readthedocs requirements.

------------------

- use shields.io badges in the README.

------------------

- use B3J0F_CONF_DIR environment variable in order to get default FileConfDriver default path for given conf files. Otherwise, use '~/etc' path.

----------------

- remove retrocompatibility with python2.6

------------------

- add __all__ in modules and packages
- add base classes in packages
- fix UTs in all python versions but 2.6