Patch: permit explicit sid to be set on resolver URL

[Frank Bennett]

I have uploaded a simple but as-yet-untested patch that permits users
to set an explicit sid on the resolver address in the preferences ->
general menu. If someone who has this need can apply this to an
instance of Zotero (it was written against Z 2.0) and report back to
the list on whether it works, it will improve the chances of takeup in
Zotero main.

The filename is resolver-sid.patch

Frank Bennett