rpc rewrite: control RPCs using gRPC + separate RPC for data transfer

transport/ssh: update go-netssh to new version
    => supports CloseWrite and Deadlines
    => build: require Go 1.11 (netssh requires it)

rpc/dataconn/timeoutconn/timeoutconn_debug.go

@@ -0,0 +1,19 @@
+package timeoutconn
+
+import (
+	"fmt"
+	"io"
+)
+
+const debugReadvNoShortReadsAssertEnable = false
+
+func debugReadvNoShortReadsAssert(expectedLen, returnedLen int64, returnedErr error) {
+	readShort := expectedLen != returnedLen
+	if !readShort {
+		return
+	}
+	if returnedErr != io.EOF {
+		return
+	}
+	panic(fmt.Sprintf("ReadvFull short and error is not EOF%v\n", returnedErr))
+}