Fix HttpFeed so again reuses polls

- If two sensors make the same http request (with just
  different post-processing on the result) then just poll
  once and pass the result to each.

  Was broken by switching to Supplier<URI> instead of just
  a simple URI, so hashcode/equals failed.
* fixed issue with release-notes page containing Liquid error: 757: unexpected token at 'Liquid error: No such file or directory - /Users/alex/Data/cloudsoft/dev/gits/brooklyn/docs/start/../../toc.json'
* fixed issue with getstartrelease notes page containing 404
added html file extension for the release-notes
Merge pull request #654 from pveentjer/0.5

* fixed issue with release-notes page containing Liquid error: 757: unex...
Fix change-version.sh

- previously excluded any file contain log or war, rather than
  just .log and .war
- previously excluded any file with "." in a dir on its path,
  rather than just . at the start of dir name
Merge pull request #657 from aledsage/cherrypick/change-version-script-fix

Fix change-version.sh
Fix EntityManagementSupport race for changeListener

- Fixes race where effector called post-exec listener concurrent
  with app.stop(), which unmanaged the app.
  Caused exception, and thus test's tearDown to fail.
Fix memento/rebind of AbstractController

- serverPoolTargets has entities as keys, so needed to fix
  MementoTransformer.transformIdsToEntities so it converted
  keys and values correctly.
- Can revisit this in the future for instead using serialised
  form of an entity-ref, rather than just String perhaps.
Remove old monitored-cassandra-cluster example project
Merge pull request #663 from grkvlt/0.5-redis

Add jemalloc library to installed packages for Redis
Merge pull request #661 from grkvlt/0.5-remove-old-example

Remove old monitored-cassandra-cluster example project
Merge pull request #659 from aledsage/cherrypick/AbstractController-memento-fix

Fix memento/rebind of AbstractController (0.5)
Merge pull request #652 from aledsage/fix/HttpFeed-reuses-polls

Fix HttpFeed so again reuses polls
resolves the issue with:
java: brooklyn.entity.rebind.Rebindable cannot be inherited with different arguments: <brooklyn.mementos.EntityMemento> and <>

This is done by dropping generics for the Rebindable, but relying on coveriant return types for getMementoSupport. Provides the same typesafety, at the price of a bit more code.
Fix thread-safety in NonDeploymentManagementContext
Merge pull request #670 from pveentjer/0.5

resolves the issue with:
Merge pull request #658 from aledsage/cherrypick/EntityManagementSupport-race

Fix EntityManagementSupport race for changeListener (0.5 branch)
New entity for Apache Kafka messaging
Added test using Kafka API and example application
Wait for JMX availability before setting SERVICE_UP