Counter creation and count retrieval methods updated.

Need to implement increment/decrement count. Need to find atomic way to update count
without vendor specific queries.
Andes Context Store message counters rdbms implementation
Merge pull request #76 from Asitha/queue-counting

Queue counting Implementation for RDBMS
Docs added
Merge pull request #80 from Asitha/doc-update

Java docs added
Merge pull request #77 from sajinidesilva/slots_Imp

refactored code
improving logs and stopping errors when cassandra is down.
Merge pull request #81 from abeykoon/add_andes_improvements

improving logs and stopping errors when cassandra is down.
issues related to logging in storage implementation fixed.
Merge pull request #82 from Asitha/log-fixes

issues related to logging in storage implementation fixed.
H2 memory storage classes updated with queue_counter tables
	modified:   modules/andes-core/broker/src/main/java/org/wso2/andes/store/jdbc/h2/H2MemAndesContextStoreImpl.java
	modified:   modules/andes-core/broker/src/main/java/org/wso2/andes/store/jdbc/h2/H2MemMessageStoreImpl.java
Improving message store manager strategies.
Merge pull request #84 from abeykoon/improve_storing_manager_new

Improving message store manager strategies.
fixing null pointer. Removing initialize method of message store manager interface and doing it via constructor.
Merge pull request #85 from abeykoon/remove_initialize_from_messageStoreManager

Removing initialize method of message store manager
Merge pull request #86 from Asitha/H2-mem-update

H2 memory storage classes updated with queue_counter tables
Changes did after profiling
changed test class
profile test changes