Move PerformanceTestUtils from core to usage/test-support
Adds load tests

- testing number of concurrent apps that can be started, and number
  of apps that can be managed.
Adds basic instructions for setting up IDEA Intelli-J, and also some debugging tips
Adds resolution to IntelliJ compilation issue, with reply from JetBrains
Javadoc
don't let stringify convert `null` to `"null"`
compute UPTIME sensor
fix bug where nginx up-detection continued to run after service stoppage
remove the hand from sensor/config values, as they aren't clickable
use generics for RendererHint, simplify class hierarchy there, and add support for rendering based on class type, used for Duration and HostAndPort, and for Entity instances to show the name of the entity
Remove apache header from install config files

- These are files "without any degree of creativity" from the
  perspective of the Brooklyn/Apache contribution.
  These files originate from the install artefacts of things to be
  installed, and are often templated to make it easier to inject
  port numbers etc.
Remove apache headers from web-docs

- These files are only used to generate the brooklyn web-site.
  Including the apache header results in a lot of noise in the 
  code/configuration snippets within those web-pages.
Remove apache header from archetype files

- The maven archetype are files "without any degree of creativity". 
  They are intended purely as a template to generate a new project 
  for a user, where upon the user can write their code within this 
  new project.
Mark `HasNetworkAddresses` as @Beta
For “install config files”, add to NOTICE

- for config files we’ve copied from other projects, add a reference
  to each in NOTICE
Add license header to SudoTtyFixingCustomizer
This closes #215
Log.warn about last build with io.brooklyn maven group id
BROOKLYN-71: DelegateSecurityProvider listens to property changes

Reloads the provider when notified and forces existing sessions to
reauthenticate.
This closes #216