Slightly improved update checker feedback

Changelog.txt

@@ -26,6 +26,7 @@ Version 1.4.07-dev
  ! Admin and Party chat prefixes are now customizable
  ! Changed the color of party leader names in Party chat
  ! Improved profile saving
+ ! Slightly improved update checker feedback
  ! Updated localization files
  ! Party item share category states are now saved when the server shuts down.
  ! When using Super Breaker or Giga Driller abilities extra tool durability is used (again)

src/main/java/com/gmail/nossr50/util/UpdateChecker.java

@@ -47,7 +47,8 @@ public class UpdateChecker {
                     oldVer = Integer.parseInt(oldTokens[i]);
                 }
                 catch (NumberFormatException e) {
-                    oldVer = 0;
+                    mcMMO.p.getLogger().warning("Could not get information about this mcMMO version; perhaps you are running a custom one?");
+                    return false;
                 }
 
                 if (oldVer < newVer) {