BROOKLYN-79: enable write access to persistence for BrooklynLauncher

And no need for OSGi when copying state
BROOKLYN-78: copy-state command copies nodes directory
Fix BrooklynJacksonSerializerTest

The addition of a RendererHint to AbstractEntity meant that the server
was adding formatting to the representation of the entity. Adding the
'raw' query parameter instructs the server to respond with JSON instead.
This closes #248