Added file-io base URL config property getters.

Updated the fileUploadServlet constant.
# WARNING: head commit changed in the meantime

IN PROGRESS - issue CORE-4126: 
https://pods.iplantcollaborative.org/jira/browse/CORE-4126

Added ability to force the removal of an announcement from the
announcer.

The announcer now fires an event when an announcement is removed.
IN PROGRESS - issue CORE-4126: Add new system message announcement to
DE. 
https://pods.iplantcollaborative.org/jira/browse/CORE-4126

The announcement removal event now tracks whether or not the
announcement was actually announced before it was removed.
Ongoing changes