Make a CID from an Ecto Changeset

[nelsonic]

• Given an ECTO changeset, return a cid (hash).

[RobStallion]

#21 will work with an Ecto.changeset. Ecto changesets are structs themselves, which means that we can call Map.from_struct/1 on a changeset and get a map.

That map can then be turned into a JSON string, hashed and turned into a CID.