Performance fixes
1) clear collections and make them available for GC
2) Migrated FlushStack implementation from java.util.Stack to java.util.Dequeue.
3) Added test cases.
Merge branch 'trunk' of github.com:impetus-opensource/Kundera into trunk

Conflicts:
	kundera-redis/src/main/java/com/impetus/client/redis/RedisClient.java