Add Title API for Minecraft 1.8.

Adds an API for the Titles added in Minecraft 1.8. There is already a pull request in #106, but this one is slightly different:
- Fluent API, multiple calls can be chained.
- Added missing ways to clear or reset the titles.
- Improved and more detailed Javadocs.

#### Example Usage
```java
player.sendTitle(game.createTitle()
    .reset() // Reset the previous title first
    .title("Sponge")
    .subTitle("http://www.spongepowered.org/")
    .stay(2400) // Stay for 1 minute
);

// Reset the previously sent title
game.createTitle().reset().send(player);
```