- Removed extra parameter defining the tests suite we are running,
  remembering current test suite in a static variable instead.
- Added SAFT_START_SUITE and SAFT_STOP_SUITE in order to manage
  current test suite.
- Renammed 'struct saft_test_results' to 'struct saft_test_suite'.
- Renammed 'SECTION' to 'SUITE'.
Added SAFT_RETURN_CODE in order to define if a test suite is a success or not.