The blockchain_client should have 'get_unspents' and 'broadcast_transction' members to be useable.  This change allows us to insert a new blockchain_client implementation, e.g. for testing a pybitcoin application.
The blockchain_client should have 'get_unspents' and
'broadcast_transction' members to be useable.  This change allows us to
insert a new blockchain_client implementation, e.g. for testing a
pybitcoin application.

blockstack/pybitcoin