Changing input data check to info level

- The 'Wrong fields' message in predictions were logged as error and
  are changed to info
Updating version to 0.7.4 plus cleaning
Adding en-gb to locale alternatives
Bug fixing: temporal patch for the confidence=None error in regressions
Bug fixing: using raise instead of sys.exit
Rephrasing history log entry
Adding history log entry
Removing final dot in history
Changing predictions in tests according to the backend split change
Merge branch 'master' into next

Conflicts:
	HISTORY.rst
	bigml/__init__.py