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).

let me know if anything important.  for me it looks sensible enough:

```
% git log -p  ./usage/launcher/src/test/resources/basic-empty-app-and-entity-blueprint.yaml
commit bcb58285734bd5589770e8898edfd6601751cc10
Author: Alex Heneveld <alex.heneveld@cloudsoftcorp.com>
Date:   Mon Sep 8 22:18:55 2014 +0100

    bring policy config setting in line with entity config, now support JSON; and fix tests

diff --git a/usage/launcher/src/test/resources/basic-empty-app-and-entity-blueprint.yaml b/usage/launcher/src/test/resources/basic-empty-app-and-entity-blueprint.yaml
index 96b1fff..2a8348a 100644
--- a/usage/launcher/src/test/resources/basic-empty-app-and-entity-blueprint.yaml
+++ b/usage/launcher/src/test/resources/basic-empty-app-and-entity-blueprint.yaml
@@ -1,3 +1,21 @@
+#
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#  http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+#
 name: Simple 2 Element
 
 location: localhost

commit 21c243ae70999f31307f57ba5841ea27f90eea5d
Author: Alex Heneveld <alex.heneveld@cloudsoftcorp.com>
Date:   Mon Sep 8 08:37:47 2014 +0100

    move config and lifecycle to new "advanced" tab; and make config page have same hover menu like sensors

diff --git a/usage/launcher/src/test/resources/basic-empty-app-and-entity-blueprint.yaml b/usage/launcher/src/test/resources/basic-empty-app-and-entity-blueprint.yaml
new file mode 100644
index 0000000..96b1fff
--- /dev/null
+++ b/usage/launcher/src/test/resources/basic-empty-app-and-entity-blueprint.yaml
@@ -0,0 +1,12 @@
+name: Simple 2 Element
+
+location: localhost
+
+services:
+- type: brooklyn.entity.basic.BasicApplication
+  brooklyn.config:
+    key1: val1
+  brooklyn.children:
+  - type: brooklyn.entity.basic.BasicEntity
+    brooklyn.config:
+      key2: val2
```