Flesh out the unmanaged API

[skeet70]

#200 added unmanaged streaming crypto, and #33 added support for unmanaged regular crypto.

We're still missing a lot of the tools to effectively use unmanaged documents (revoke/grant access unmanaged for ex). See the reference IronOxide implementation for what's missing at the time this is worked.

[coltfred]

documentGetMetadata, documentGetIdFromBytes, documentGetIdFromEdeks, documentGrantAccess, documentRevokeAccess are the missing functions.