adding apis and store for provisioner information, such as the
number of workers running on each provisioner for each tenant.
removing unused code with provisioner status and assign time, and
adding a convenience function for getting a db connection with
auto commit on since thats the vast majority.
fixing heartbeat and expire bugs, and adding more logging.
adding more unit tests.
add documentation for superadmin provisioner apis and changelog.
adding docs for config settings for provisioner requests and
doing some cleanup to simplify building the http client.
Merge remote-tracking branch 'origin/develop' into feature/provisioner-apis

Conflicts:
	server/src/main/java/com/continuuity/loom/common/conf/Constants.java
	server/src/main/java/com/continuuity/loom/common/queue/guice/QueueModule.java
	server/src/main/java/com/continuuity/loom/scheduler/JobScheduler.java
	server/src/main/java/com/continuuity/loom/scheduler/task/ClusterService.java
	server/src/test/java/com/continuuity/loom/BaseTest.java
	server/src/test/java/com/continuuity/loom/http/LoomServiceTestBase.java
pull request changes.  Adding more comments and javadocs. Also,
make sure a tenants workers have been set to 0 before deleting it.
This is to make it clear to the caller the behavior of the delete.
No additional tasks will be performed for the tenant since it has
no workers.
Merge remote-tracking branch 'origin/develop' into feature/provisioner-apis
more pull request changes. Removing unused code, adding more
comments and moving provisioner timeout logic to its own thread
so that the TenantProvisionerService can be used everywhere
without starting/stopping.
Merge remote-tracking branch 'origin/develop' into feature/provisioner-apis

Conflicts:
	CHANGELOG.md
	server/src/main/java/com/continuuity/loom/codec/json/JsonSerde.java
	server/src/main/java/com/continuuity/loom/http/handler/LoomSuperadminHandler.java
	server/src/main/java/com/continuuity/loom/runtime/LoomServerMain.java
	server/src/main/java/com/continuuity/loom/store/entity/SQLAdminEntityStoreView.java
	server/src/test/java/com/continuuity/loom/BaseTest.java
	server/src/test/java/com/continuuity/loom/http/LoomSuperadminHandlerTest.java
Merge pull request #277 from continuuity/feature/provisioner-apis

Feature/provisioner apis