srm: Fix a few IllegalStateTransition errors in srmLs

Besides supressing the errors, the code refactors state related
checks, renames the State#isFinalState method, and deletes the
static variant of the method (per reviewer request).

Target: trunk
Require-notes: no
Require-book: no
Acked-by: Paul Millar <paul.millar@desy.de>
Patch: http://rb.dcache.org/r/6238/