Add new API calls for setting favorited accounts, listing favorites and
unregistered accounts

Previously there was no way to mark an account as a favorite. Now this
can be done using the wallet_account_set_favorite API call. Also, there
are new listing calls wallet_list_favorite_accounts to list all accounts
with favorited status, and wallet_list_unregistered_accounts to list all
accounts created locally but not registered on the blockchain.
Merge branch 'master' of github.com:BitShares/bitshares_toolkit