Added creation of keyspace

 - Now creates Cassandra keyspace and its various options defined in the
   connectionDetails map using the KeyspaceActionSpecificationFactoryBean.
 - Options include durableWrites, replicationFactor, replicationStrategy,
   networkTopolgy
 - Removed Spring Data Cassandra Factory beans creation methods, the
   beans are now settable to allow overriding and are now destroyed on
   destroy().
 - Used ConfigObject throughout instead of connectionDetails so can access
   nested maps properly.
 - GormCassandraSessionFactoryBean moved to separate file.
 - Renamed constants removing cassandra prefix as it is redundant.
 - ConfigUtils.read method inlined as connectiondetails can have non-string
   values when a ConfigObject is passed in from Groovy.
 - added validation of property Enums.