Migrate to new project structure.

libp2p/transport/upgrader.py

@@ -0,0 +1,27 @@
+from libp2p.stream_muxer.mplex.mplex import Mplex
+
+
+class TransportUpgrader:
+    # pylint: disable=no-self-use
+
+    def __init__(self, secOpt, muxerOpt):
+        self.sec = secOpt
+        self.muxer = muxerOpt
+
+    def upgrade_listener(self, transport, listeners):
+        """
+        upgrade multiaddr listeners to libp2p-transport listeners
+
+        """
+
+    def upgrade_security(self):
+        pass
+
+    def upgrade_connection(self, conn):
+        """
+        upgrade raw connection to muxed connection
+        """
+
+        # For PoC, no security, default to mplex
+        # TODO do exchange to determine multiplexer
+        return Mplex(conn)