start of some security group work
move @sjcorbett's security group customizer to a networking subdir, and add some WIP classes to facilitate defining security groups
improve logging for longevity tests
refactor EntityCleanupLongevityTest so that (1) it checks explicitly that things have been cleaned up, (2) we have a unit test as well as a long-running test, and (3) the long-running test makes memory assertions; currently explicitly excuses certain leaks (which we want to patch soon)
reply to code review comments, method now called `isMostlyEmpty`
Extract BrooklynLauncherRebindTest from BrooklynLauncherTest
Adds high availability management-plane support

- support for standby management-node(s), where one is automatically promoted
  to master when the current master fails or terminates
REST api: high-availability / management-plane queries
add configuration for rat plugin
add a utility findEffector to assert that effectors have been defined
improve test leak logging
rename HttpPollValue to HttpToolResponse, and minor other tweaks to HttpFeed code
change usages of HttpPollValue to HttpToolResponse
REST resource tests share common setUpResources method
convenience for adding a tag to a task dynamically
avoid NPE resolving camp yaml
jsonya now no-op if put(null), previously threw NPE
create a pure java repeater in utils, and deprecate the groovy-based repeater in core, and notes on Asserts which prompted the confusion which led to these changes
use new util Repeater rather than the now-deprecated groovy internal one
introduce a test fixture for REST API tests which use the launcher (ie an actual web server, rather than the lightweight one used by most resource tests)