GUI+REST improvements - yaml spec and advanced tab for entities

This adds some oft-requested functionality to the GUI and REST API:

* You can add children given a YAML spec
* Problem indicators are included in the summary reason when an entity is on-fire
* You can clear the problem indicators (so enrichers re-populate them if the problem recurs)
* You can see the blueprint YAML on the Summary tab
* You can rename an entity
* The REST API supports setting config and sensors (and policy config set has been fixed)

It also restructures the GUI (moving lifecycle, config, and some new things to the "Advanced" tab) and improves JSON rendering (using a Brooklyn-specific ObjectMapper).

Seems the events are a bit askew. When I try to use the float menu:
* I place my mouse over the down arrow.
* The menu appears.
* I move the mouse to the first menu entry.
* The menu disappears!
* I move the mouse to the down arrow again.
* The menu reappears.
* I can move the mouse to and select the first entry.