BrooklynNode cluster + upgrade effector

Also effectors to:
  * select master in the cluster
  * set HA priority
  * set HA state
Regarding changing indent: there is an unfortunate mix of 4 versus 8 space indents for things like this. I'm a big fan of the 8 space indent for a line that is split across multiple lines (so it's clear it is not just the next line of code). 

That is the convention in almost all code that I see (e.g. in google coding convention [1], in oracle coding convention, in jclouds, etc).

I'm also a fan of consistency within a class (so go with what's there), but unfortunately this class has a mix.

[1] https://google-styleguide.googlecode.com/svn/trunk/javaguide.html#s4.5.2-line-wrapping-indent