Better default gora-sql-mapping.xml with larger field sizes for MySQL

The current generic default gora-sql-mapping.xml has field sizes that are too small in almost all situations when used with MySQL. I have included a mapping which will work better for MySQL (takes slightly more space but will be able to handle larger fields necessary for real world use). Includes patch from Nutch-1490 and resolves the non-Unicode part of Nutch-1473. I believe it is not possible to use the same gora-sql-mapping for both hsqldb and MySQL without a significantly degraded lowest common denominator resulting. Should the user manually rename the attached file to gora-sql-mapping.xml or is there a way to have Nutch automatically use it when MySQL is selected in other configurations (Ivy.xml or gora.properties)?