Connect pion library logger with snowflake log

We need to set up the pion/webrtc logger to write output to the
snowflake log, otherwise the warnings we are getting from the pion
library are being lost.

Note: this requires go version 1.13 and later in order to use the
`log.Writer()` function.

client/lib/webrtc.go

@@ -9,6 +9,7 @@ import (
 	"time"
 
 	"github.com/dchest/uniuri"
+	"github.com/pion/logging"
 	"github.com/pion/webrtc"
 )
 
@@ -154,7 +155,14 @@ func (c *WebRTCPeer) preparePeerConnection() error {
 		c.pc.Close()
 		c.pc = nil
 	}
-	s := webrtc.SettingEngine{}
+
+	logFactory := logging.NewDefaultLoggerFactory()
+	logFactory.DefaultLogLevel = logging.LogLevelError
+	logFactory.Writer = log.Writer()
+
+	s := webrtc.SettingEngine{
+		LoggerFactory: logFactory,
+	}
 	s.SetTrickle(true)
 	api := webrtc.NewAPI(webrtc.WithSettingEngine(s))
 	pc, err := api.NewPeerConnection(*c.config)