Added task execution framework
Migrated graph over to new task executor
Added events and task cleanup
Converted tasks to ForkJoin tasks to allow for parallel execution.
Added tests for the log entry iterator
Finished testing of the EntityVersionCleanupTask
Revert "Converted tasks to ForkJoin tasks to allow for parallel execution."

This reverts commit dc3f448c946219c44e3dbfadb294fea0b8048343.

The ForkJoinPool does not have the following characteristics

Ability to name a pool
Ability to set queue size for rejection

As a result, it is not well suited for our asynchronous I/O tasks, and I'm moving back to ExecutorService

Conflicts:
	stack/corepersistence/collection/src/main/java/org/apache/usergrid/persistence/collection/impl/EntityVersionCleanupTask.java
	stack/corepersistence/common/src/main/java/org/apache/usergrid/persistence/core/task/ImmediateTask.java
	stack/corepersistence/common/src/main/java/org/apache/usergrid/persistence/core/task/NamedTaskExecutorImpl.java
	stack/corepersistence/common/src/main/java/org/apache/usergrid/persistence/core/task/Task.java
	stack/corepersistence/common/src/main/java/org/apache/usergrid/persistence/core/task/TaskExecutor.java
	stack/corepersistence/common/src/test/java/org/apache/usergrid/persistence/core/task/NamedTaskExecutorImplTest.java
	stack/corepersistence/graph/src/main/java/org/apache/usergrid/persistence/graph/serialization/impl/shard/ShardGroupCompaction.java
	stack/corepersistence/graph/src/main/java/org/apache/usergrid/persistence/graph/serialization/impl/shard/impl/ShardGroupCompactionImpl.java
Finished updating back to executor pool
Merge branch 'two-dot-o' into eventsystem
Removed stress tests that should not be part of the build
Resolved conflicts when guice modules are integrated
Merge branch 'two-dot-o' into eventsystem
Refactored listener to take buffers of versions for efficiency

Refactored task to use RX for observable streams
Merge branch 'two-dot-o' of https://git-wip-us.apache.org/repos/asf/incubator-usergrid into eventsystem
Merge branch 'eventsystem' into two-dot-o