v0.7.0

What's Changed

• Rebrand to celestiaorg by @evan-forbes in #42
• update to the latest merkletree commit by @evan-forbes in #43
• fix diagram by @liamsi in #44
• Reuse hash by @liamsi in #40
• Adhere to specs and hash the nid in leaf by @liamsi in #47
• Remove interval digests in favor of []byte by @evan-forbes in #48

Full Changelog: v0.5.0...v0.7.0