Update testbed modules (#360)

* Update testbed go.mod

These are different than the ones on root and if you use an IDE (depending on the settings) these files may get automatically changed constantly. This update to go.mod avoids that.

* Run go mod tidy for testbed

testbed/go.mod

@@ -6,9 +6,10 @@ require (
 	contrib.go.opencensus.io/exporter/jaeger v0.1.1-0.20190430175949-e8b55949d948
 	github.com/open-telemetry/opentelemetry-service v0.0.0-20190625135304-4bd705a25a35
 	github.com/shirou/gopsutil v2.18.12+incompatible
-	github.com/spf13/viper v1.4.0
-	github.com/stretchr/testify v1.3.0
-	go.opencensus.io v0.22.0
+	github.com/shirou/w32 v0.0.0-20160930032740-bb4de0191aa4 // indirect
+	github.com/spf13/viper v1.4.1-0.20190911140308-99520c81d86e
+	github.com/stretchr/testify v1.4.0
+	go.opencensus.io v0.22.1
 )
 
 replace github.com/open-telemetry/opentelemetry-service => ../