add tag json and potted versions of saplings, fixes #24, #25, and #26

[ix0rai]

simple pull request to add blocks and items to their proper tags and to add potted saplings

• add larch, hazel, and maple saplings to item sapling tag and block sapling tag
• add larch, hazel, and maple leaves to item leaves tag and block leaves tag
• add blueberries to fox_food tag
• add potted saplings

fixes #24 fixes #25 fixes #26

[ix0rai]

which branch should this target? I noticed development moved to 0.9.0-1.19, but I think I could move this to master too