re-activates MiniREEF evaluator
* fixes #189, loading of p2unified.rdf
* still, p2 depends mostly on the pronom id, which is not present for most migration actions
completes simple version of notification api
* notifications can be PUT, and if an matching email is provided a notification is stored for the user. refs #202
fixes #236, crash after enabling discarded alternative
* when importing a plan links from values to scales have been established only for enabled alternatives. But alternatives can be discarded when they are (partially) evaluated. therefore the links for all values have to be established.
adds simple REST notification endpoint, fixes #202
* to activate the endpoint, credentials for basic authentication have to be defined in PLATO's configuration.properties:
  notification.rest.user, notification.rest.pass
* notifications can be posted if there is a planner with the given email address -
  they are displayed when the planner logs into PLATO as info messages.

Further improvements:
* use of url rewriting solution like http://ocpsoft.com/prettyfaces/
  this would allow to provide links to directly open plans (in the notification, as well as in emails) or revise existing plans.
adds more plan statistics, refs #20