Merge pull request #1 from benjello/master

Fixing test_irrp and starting ppe tests
Add comments.
Remove bad import.
Remove country parameter.
Remove unused get_config function.
Simplify XAxis.
Add nmen parameter to web API.
Add xaxis parameter to web API.
Rename xaxis to x_axis.
Remove trailing spaces from lines.
Move TaxBenefitSystem class in its own module.
Rework web API to allow several scenarios.
Preserve order of items in JSON dictionaries received in web API tests.
Cleaning obsolete comments
Add 2014 to copyright years.
Correct variable name in test (thanks Mahdi).
Refactor TODOs
Replace descriptions with ordered dicts.
Replace wrong type "integer" with "float" in params XML.
Remove unused attribute "taille" from BAREME in params XML.