[WIP] Scoreboard 1.8

Update the scoreboard api for 1.8 clients. Based on the scoreboard branch from @SpaceManiac . 
The color feature from the scoreboard teams isn't complete implemented yet. In my opinion it needs some discussion what's the best way is to implement it.
So it's also not fully tested, but all possible values that will be sent are valid. (Chat color codes or -1 as reset)
All other implemented things are minor tested.

Changes:
* Add missing codecs and so missing features
* Add missing Override annoations
* Change a couple of integer values to VarInt
* Fix missing order of some packet values

Testing material:
* Source: https://gist.github.com/games647/8dd1fba7695c8553228a
* File: https://www.dropbox.com/s/j7jfs3yezknbrlp/ScoreboardTest.jar
* Just for testing propose.
* Example command: /test team xyz register

Related GlowKit ticket https://github.com/GlowstoneMC/GlowKit/pull/16
Related to #81 

ToDo: 
* Implement missing display slots.
* Make a complete rebase after review?

Questions:
Should [this](https://github.com/games647/Glowstone/blob/scoreboard1.8/src/main/java/net/glowstone/scoreboard/GlowTeam.java#L71) be done by a method, enum value or is this okay?
[Enum, boolean or String](https://github.com/games647/Glowstone/blob/scoreboard1.8/src/main/java/net/glowstone/scoreboard/GlowObjective.java#L111)? (It's currently implemented as enum on vanilla servers, so they may add more)
Should update packets only be sent on changes?