Instead of OperationalException and IntegrityException will be raised
for the following eror types:
ER_BAD_NULL_ERROR, ER_DATA_OUT_OF_RANGE, ER_CONSTRAINT_FAILED, ER_DUP_CONSTRAINT_NAME
- added a thin python wrapper around mariadb module
- added constansts under mariadb.constants (CLIENT, CURSOR, INDICATOR)
- bench and test are now in testing subdirectory
- updated documentation