Support for MySQL BIT(M) data type proper default values

CMysqlColumnSchema: support for MySQL BIT(M) data type proper default values.
For example, MySQL (MariaDB) return default value as "b'1'" string, not as "1", so, this case should be considered especially. See also http://dev.mysql.com/doc/refman/5.0/en/bit-type.html
NOTE: This patch support M = [1..32] only, but MySQL support M = [1..64]