adding cassandra tests
Merge branch 'develop' of github.com:Stratio/stratio-deep into develop

Conflicts:
	deep-cassandra/src/main/java/com/stratio/deep/cassandra/cql/DeepRecordReader.java
	deep-cassandra/src/main/java/com/stratio/deep/cassandra/util/CassandraUtils.java
	deep-commons/src/main/java/com/stratio/deep/commons/extractor/utils/ExtractorConstants.java