[ZF3] Forward plugin doesn't detach problem listeners anymore.

[nathanjosiah]

Looks like there was a regressions as part of a v2 compatibility removable commit. The detachProblemListeners code builds the list of listeners to remove but doesn't actually remove them. For me, this manifests as my resulting ViewModel being double-rendered due to the InjectViewModelListener not actually being detached.

I will submit a PR to restore the block of code that actually detaches the listener.

[nathanjosiah]

@froschdesign What do I need to do to get this moving forward? I think this is the last issue preventing my team from upgrading to ZF3. My PR includes tests for both the attachment and detachment of the listeners.