Persist and rebind feeds

- Adds Feed interface
- Adds abstractEntity.addFeed; if added like that then feed is persisted
- Adds EntityInternal.getFeedSupport(), which has getFeeds(), addFeed(),
  removeFeed() and getAllFeeds()
- AbstractFeed.poller: make private, with getter;
  and make transient
FunctionFeed: test persistence

- and make easier to build a FunctionPollConfig
Test rebinding SshFeed
Persist JmxFeed: testing and transient fields
Experimenting with Feed as EntityAdjunct
Tidy ChefAttributeFeed
Convert Feed to extend EntityAdjunct
Adds IllegalStateExceptionSupplier.EMPTY_EXCEPTION

- don’t create a new instance every time a Maybe.absent is constructed
BROOKLYN-55 install script for brooklyn
Force UNIX-style line endings on shell scripts
HTTP API entity helpers
Support for timeout parameter in the /server/shutdown request
Shutdown effector in BrooklynNode
Brooklyn node safe STOP effectors

  * Stop but leave apps running
  * Stop apps and stop node
Refuse stop of Brooklyn Node if there are child apps

(possibly mirrored child apps added manually)
Support HTTP responses with empty body.
Adds persister.loadMementoRawData

- Refactors BrooklynMementoPersisterToObjectStore to remove duplication
- Adds BrooklynMementoRawData, which has the contents of the raw
  blobs/files for persistence (rather than deserialised mementos)
- Adds BrooklynMementoPersisterToObjectStore.loadMementoRawData
- Adds BrooklynMementoPersisterToObjectStore.checkpoint(BrooklynMementoRawData)
copy-state CLI: use BrooklynMementoRawData
CLI copy-state supports uploading to any location

- previously could only copy to the filesystem, rather than to
  any object store
Transformations of persisted state