Fix several MonetDB Bulk Loader issues

[PDI-10169] MonetDB Bulk Loader Step Ignore Truncate Table checkbox
- Pass unquoted schema and table separately when getting a truncate statement 
[PDI-12014] Incorrect data type used for string columns when creating tables in MonetDB
- Use STRING is length is unknown
[PDI-12278] MonetDB Bulk Loader error with MonetDB Jan 2014-SP2 bugfix release
- Do not make a second call to to data.out.writeLine( "" ) (by Juan Carlos)