app/matrix/appservice-irc: add ignoreIdleUsersOnStartup option

This should alleviate an issue of people getting joining and immediately
getting dropped off due to client limit on bridge restarts.

Change-Id: Ideb13ba9930d565ede728d2750d0c7af04746cf1

app/matrix/lib/appservice/appservice-irc.yaml

@@ -239,6 +239,16 @@ ircService:
         #      initial: false
         #      incremental: false
 
+        # Should the bridge ignore users which are not considered active on the bridge
+        # during startup
+        ignoreIdleUsersOnStartup:
+          enabled: true
+          # How many hours can a user be considered idle for before they are considered
+          # ignoreable
+          idleForHours: 72
+          # A regex which will exclude matching MXIDs from this check.
+          # exclude: "foobar"
+
       #mappings:
         # 1:many mappings from IRC channels to room IDs on this IRC server.
         # The matrix room must already exist. Your matrix client should expose