Automatically remove inactive party members after 7 days (default)

Inactive meaning, the player has offline for atleast 7 days. This will
prevent the parties.yml file from getting unnecessarily large.

src/main/java/com/gmail/nossr50/skills/runnables/PartyAutoKick.java

@@ -0,0 +1,35 @@
+package com.gmail.nossr50.skills.runnables;
+
+import java.util.ArrayList;
+
+import com.gmail.nossr50.mcMMO;
+import com.gmail.nossr50.config.Config;
+import com.gmail.nossr50.party.Party;
+import com.gmail.nossr50.party.PartyManager;
+
+public class PartyAutoKick implements Runnable {
+
+    @Override
+    public void run() {
+        updatePartyMembers();
+    }
+
+    private void updatePartyMembers() {
+        long currentTime = System.currentTimeMillis();
+        long kickTime = 24L * 60L * 60L * 1000L * Config.getInstance().getAutoPartyKickTime();
+
+        ArrayList<Party> parties = new ArrayList<Party>(PartyManager.getParties());
+
+        for (Party party : parties) {
+            ArrayList<String> members = new ArrayList<String>(party.getMembers());
+            for (String member : members) {
+                long lastPlayed = mcMMO.p.getServer().getOfflinePlayer(member).getLastPlayed();
+
+                if (currentTime - lastPlayed > kickTime) {
+                    System.out.println("Removing " + member + " from " + party.getName()); // Debug, remove this later
+                    PartyManager.removeFromParty(member, party);
+                }
+            }
+        }
+    }
+}