Brooklyn node and cluster upgrade

Merges #266 (cluster upgrade) with work I've been doing on node upgrade.

Builds on #260 so please ensure that is merged first.

Needs further testing (by me at this point) but wanted to push it in case @neykov you have comments, especially on the last commit.
agree - have refactored, actually preferring to return a builder.  putting `body(Repeater)` on the builder feels to specialized so instead there are now methods in `Tasks` which generate a builder from a `Repeater`.