Added BiomeTypes.
Merge pull request #271 from SpongePowered/feature/biomes

Added BiomeTypes.
Fix wrong spelling.
Add method to get running time in ticks
Clarify running tick time javadoc
Add World Border API
Remove most static methods and unify 'valueOf'/'values' functions on GameRegistry
add method to check if a plugin/mod with a specific ID is loaded, fixed build.gradle spelling error
Refactor Scheduler to use Objects instead of PluginContainers, leaving implementation to figure out which is which.