Add basic support for multiaddr addresses and improvement around peer id (#75)

* Improved peer ID construction and usage

* peer id object is directly passed to the network

no need to cast from a string to an ID

* don't base64 encode the peer id when loading from public key

* use proper multiaddr address

- keep multiaddr object into peerstore instead of string
- update network code to use new multiaddr lib
- update tests and example

* don't instanciate peerstore object in constructor

This has side effect where the same peerstore
is used for different instance of Libp2p

* add connect method to basic_host

* use zaibon's fork of sbuss/py-multiaddr

* lint

host/host_interface.py

@@ -21,6 +21,12 @@ class IHost(ABC):
         :return: mux instance of host
         """
 
+    @abstractmethod
+    def get_addrs(self):
+        """
+        :return: all the multiaddr addresses this host is listening too
+        """
+
     @abstractmethod
     def set_stream_handler(self, protocol_id, stream_handler):
         """
@@ -39,3 +45,16 @@ class IHost(ABC):
         :param protocol_ids: protocol ids that stream can run on
         :return: true if successful
         """
+
+    @abstractmethod
+    def connect(self, peer_info):
+        """
+        connect ensures there is a connection between this host and the peer with
+        given peer_info.peer_id. connect will absorb the addresses in peer_info into its internal
+        peerstore. If there is not an active connection, connect will issue a
+        dial, and block until a connection is open, or an error is
+        returned.
+
+        :param peer_info: peer_info of the host we want to connect to
+        :type peer_info: peer.peerinfo.PeerInfo
+        """