webadmin: Cleanup around Setup Networks events

* Removed NetworksChanged event that wasn't used for anything.
* Parameterized generic events.
* Fixed typo in OperationCandidateEventArgs name.

Change-Id: I23945cb33eea895b216ab78fbbca5a6a26300c7c
Signed-off-by: Lior Vernia <lvernia@redhat.com>