Added Invites (#223) * Added Invites * Fixed permission checking * Added checks and changed how invite expanding works * Added Invite.Guild and Invite.Channel * Added javadoc * Made proposed changes * Fixed NPE when guild icon is null * Added JDAClient#acceptInvite() * Removed old commented out invite code from JDA 2.0 * Added Invite#delete() * Fixed a spelling mistake in javadoc and added Invite#getJDA() * Added Channel#createInvite() and InviteAction * Added missing javadoc * Added copyright headers * Removed old commented out imports * Added Invite#accept() and JDAClient#acceptInvite(String) and made the rest of the requested changes * Fixed invite related docs * Added InviteAction#setMaxAge(long, TimeUnit) overload, fixed an NPE when resetting maxAge and maxUses to default and added missing @throws (commit: 240adf3)