Create main update.java

This is ONLY the main function. I updated some stuff in the skeleton code. For example: changed "make a post" to "gobble", added a character limit checker in the gobble function (since posts are supposed to be no more than 140 characters long) and added some safety checks to our if statements (so that people dont have to Capitalize Every First Letter like i have it displayed in the menu). If you already added these things then feel free to ignore. Just clearing up some last minute stuff.