Schema creation

By request a small schema creation tool was added.
Be advised, built for Cassandra 0.6.x versions, this tool will not create the schema in the database, it will instead create a file it the schema related info.

USE:

For the use check:

http://www.datanucleus.org/products/accessplatform_1_0/rdbms/schematool.html

Just change the references to “org.datanucleus.store.rdbms.SchemaTool” into “org.datanucleus.store.cassandra.SchemaTool” in the ant file, when executing manually, etc

Notes
- This is a beta version, inheritance relations are not treated.
- The ddl file option can be used to set the output file, by default the result goes to datanucleus.schema
- The result can then copied from the file into the Cassandra configuration file, where cache information should be added by the user, according to his needs.
- Deletion is not supported.
- Remaining options are ported from the rdbms plug-in and were not treated.