Create functions on the accumulator that match the paper

[Stentonian]

The following functions need to be written:

• public_params - salts, height, accumulator variant, group info, max liability
• root_public_data - hash & Pedersen commitment of the root of the tree
• root_secret_data - blinding factor & liability for the root
• verify_root - takes public & secret data and checks that they match

[Stentonian]

The public values should be printed out to stdout on tree creation

[Stentonian]

Do this first: https://github.com/silversixpence-crypto/dapol/issues/127