Add Banner Bukkit APIs

(Changes may come is BlockEntityTag stuff is added)
Add Banner MaterialData, and remove base colors from BlockState
Derp, wrong thing.
BannerPattern should not have a base color
Fix non-static method
NullPointerExceptions, not IllegalArgumentException
Add MaterialData for banners to Material
Deprecate magic values
Rename some pattern types to be more descriptive, and fix diagonal cross
Whoops, hanging semicolon
Merge branch 'banners' into specialrecipes