Added detection of mods that rely on Java 8 and a graceful error screen.
The nag screen will be shown once a day. It can be disabled by editing the forge.cfg.
However it is HIGHLY recomended that user update to Java 8.
Using the @Mod annotation mods can opt-in to a centrally controlled update system.
This is PURELY a notification system and will NOT automatically download any updates.
The End User can control which mods check for updates and disabel the system entirely using the Forge Config and GUI.
Format for the json the URL must point to is described here: https://gist.github.com/LexManos/7aacb9aa991330523884