ndb_cassandra: Changing root Makefile not to compile the module by default.

- Reusing existing db_cassandra module in the Makefile.groups
structure in order to not compile the ndb_cassandra module by default.

Makefile.groups

@@ -54,7 +54,7 @@ mod_list_postgres=db_postgres
 mod_list_unixodbc=db_unixodbc
 
 # - modules depending on mysql cassandra library
-mod_list_cassandra=db_cassandra
+mod_list_cassandra=db_cassandra ndb_cassandra
 
 # - modules depending on xml2 library
 mod_list_cpl=cpl-c

README-MODULES

@@ -118,6 +118,7 @@ mqueue			Message queue system for configuration file
 nat_traversal		NAT :: NAT traversal module
 nathelper		NAT :: NAT traversal module :: RTPproxy (SIPPY software)
 ndb_redis		Connector to REDIS NoSQL Database engine
+ndb_cassandra		Connector to Apache Cassandra
 osp			Open Settlement Protocol support
 outbound		SIP Outbound Implementation
 p_usrloc		Partitioned and distributed user location services