Redirect to user list on user save

Redirecting to the index was frustrating when you want to edit multiple
users
Increase incident_key to 200 chars

With descriptive hostnames in Icinga we regularly get incident key
lengths > 100 characters. CharFields become varchars in sqlite and MySQL
at least and they're cheap so set it much higher
Merge pull request #6 from DazWorrall/user-save-redirect

thanks a lot, seems great, merging it now. Merging: Redirect to user list on user save
Merge pull request #7 from DazWorrall/longer-incident-key

Increase incident_key to 200 chars