More refactoring
* Changed -J option to -s (for sp_config_file instead of
json_config_file)
* Removed logging options -d and -v, fine-grained logging configuration
is now possible from saml2test/log_configuration.py
* Changed test specification format by making the response and request
class a tuple
* Changed the output format of the test results, the results are now
stored in variable which can directly be parsed as json