Fixes hanging import

The static declaration of the user::bot_db and user::trade_db attributes
was causing the import hanging, as CPython has a global import lock,
which was causing the hanging

http://stackoverflow.com/questions/1162461/python-hangs-when-importing-swig-generated-wrapper

The module isn't debugged yet, and there may be issues with the user
constructor taking std::string instead of char *