Add more examples to Notary actor about the way how accounts can be created/used

[AnnaShaleva]

We have a nice example of Notary actor usage. However, in this example accounts for Notary actor are taken from the wallet. We need to add one more example of the way how account can be constructed not from the wallet, but in the code-level.

Another thing that we need to add is how dummy accounts are supposed to be used with Notary actor (dummy sig/multisig/contract).