improve formatting of scheduler's status
add a new main.uri sensor in Attributes, similar idea but wider scope to WebAppService.ROOT_URL
enhance config REST data to provide info so that we get "open REST link" actions, and related cleanup
include parameters in description of effector invocations
call `parentLocation.release(child)` on unmanage, so that (in part) ports obtained for use on localhost are freed up for reuse;
and clean up how the decision to `release` is made with new abstract ProvisioningLocation
add support for extracting flags from $brooklyn:entitySpec declarations and translating them as config
apply code review comments, fixing whitespace and tidying a classname
This closes #273