Merge pull request #25 from ramith/master

fixing MB-699
used CoordinatedActivity get coordinator changed notifications
used CoordinatedActivity get coordinator changed notifications
added slotWindowSize to config file and bug fixing
changed CoordinatedActivityImpl class
Merge pull request #28 from sajinidesilva/slot_Imp

Slot based message deliverey model M1
changed andes-virtualhosts.xml
Merge pull request #29 from sajinidesilva/slot_Imp

changed andes-virtualhosts.xml
changed andes-config.xml
Addidtional checks and logging added for configuration errors.
 - andes-virtualhosts file typo fixed.
cassandraServerService startup disabled.
content removal task interval in andes-config file changed from reading a milli seconds value to
a seconds value.
Unwanted zookeper and cassandra connection related methods removed

Virtual hosts config file reading updated to read multiple storage related properties
andes-virtualhosts.xml updated.
Merge pull request #27 from Asitha/jdbc-integration

storage integration
Merge pull request #30 from sajinidesilva/slot_Imp

changed andes-config.xml
added new attributes to andes-config.xml
Merge pull request #31 from sajinidesilva/slot_Imp

added new attributes to andes-config.xml
Use cassandra-driver-core instead of cql-driver
Merge pull request #32 from a5anka/cassandra_driver_change

Use cassandra-driver-core instead of cql-driver