Add support for Minecraft 1.8.x

This commit allows BungeeCord to support Minecraft clients both of versions 1.7.x and of 1.8.x. There should be no breakages to any other support, however following their deprecation and uselessness within 1.8, the Tab list APIs have been removed.

Please report any issues to GitHub and be sure to mention client, server and BungeeCord versions.

When used with an appropriate server jar (such as multi protocol Spigot), this will allow clients of many versions to concurrently be connected to the same set of servers.