[FEATURE] Configurable Redirects (Revision 15)

Adds a new entity "Redirection" and a RedirectionService that enables
basic administration of redirects.

The RedirectionService will be triggered *before* the Routing Framework
kicks in and redirects to any configured target URI if applicable.
It however is only invoked when no cached route matches the current
request. Thus, if a redirection is added, depending route cache entries
are flushed automatically.

Currently redirects can only be managed via new commands::

	./flow redirection:list
	./flow redirection:create source/path target/path
	./flow redirection:remove source/path
	./flow redirection:removeall

The plan is, however, to create them automatically as soon as related
routes become obsolete due to changed entities for example.

Change-Id: Ieee3a8412b22affe502a9d81ee9c3d98a1fce360
Releases: master
Related: #29972
Revision-Id: 0b26b3cd4bff7ad147e309c1e19699a748001409