add support for persisting to object store, including CLI --persistenceLocation taking object store syntax.
refactors file-based support to use a common PersistenceObjectStore interface backed by either filesystem or jclouds blobstore (only tested w softlayer so far).
add HA brooklyn-manager persistence to object store, and refactor previous to be cleaner
tests for volumes read and written, plus conveniences for cleaning
    addresses review comments, cleans up quite a few things.  most importantly:

    * change start sequence so that:
      * HA is known when the web console comes up (initPersistence before startWebApps)
      * launcher exits if persistence is misconfigured or if it fails to rebind

    * big tidy up of startup logging around persistence/HA
    * fix how jclouds integration tests inherit (couldn't find a nice way with any combo of @BeforeGroup / @BeforeMethod, so have just repeated all the test methods from supers)
    * support brooklyn.persistence.location.spec being set in brooklyn.properties
    * support brooklyn.persistence.backup.required (note, this defaults to false in obj store, but we seem to be pretty good about not clobbering things; even so, some prod usage may want versioning on the obj store)
    * clean up how persistence store initialization (prepare) is done
    * refactor of how object store items are written, with wrapper which handles locking, cutting code and fixing append for file and jclouds obj store
Merge branch 'master' into object-store-persistence

Conflicts:
	core/src/test/java/brooklyn/management/ha/HighAvailabilityManagerTestFixture.java
          -- new test added to master, integrated with method rename here and tested with refactoring
Merge pull request #1452 from ahgittin/object-store-persistence

add support for persisting to object store