Add f top command functionality. Resolves #71.

Gives the ability to see top Factions on the server sorted by certain criteria:
Balance: sorts by faction bank balance and all faction member balances.
Power: total power.
Land: total land claimed.
Online: members currently online.
Members: total members, online and offline.

Future criteria can be added of course.

src/main/java/com/massivecraft/factions/struct/Permission.java

@@ -73,6 +73,7 @@ public enum Permission {
     SCOREBOARD("scoreboard"),
     SEECHUNK("seechunk"),
     SETWARP("setwarp"),
+    TOP("top"),
     WARP("warp");
 
     public final String node;