Added test suite for u2py.
Now using default wsgi server with threading model.
Inroduced reader lock in card constructor.
Inroduced lock for library functions.
Added card_plus_perso handler.
Added MFPlusError for card.mfplus_personalize.
Fixed reference counting bug in transport_card.clear.
Minor fixes for handlers_base:

+ Added Content-Type header for api handler response.
+ Fixed possible bug with handlers without default arguments.
GET api documentation fixes.