Deploy across an entire web cluster

Adds deploy, undeploy, and redeployAll to webapp cluster entities (DWAC and ControlledDWAC).

Also fixes some issues noticed in how tasks are tracked and displayed.
This wasn't in 0.7.0-M1, so I'd be fine with us deleting it rather than deprecating - https://github.com/brooklyncentral/brooklyn/blob/0.7.0-M1/core/src/main/java/brooklyn/entity/group/DynamicCluster.java

@grkvlt why did you add this?

It looks like most of these methods were added post-0.7.0-M1, with some in 0.7.0-M1 (also see https://github.com/brooklyncentral/brooklyn/blob/0.6.0/core/src/main/java/brooklyn/entity/group/DynamicCluster.java).