Added clean exec functionality + ACI implementation - V2 (#244)

* Stubs and vkubelet changes

* added dependencies

* Azure provider exec implementation

* added missing dependencies

* added vkubelet imports

* added huawei exec stub

* Fixed exec tab functionality / stdin buffer length

* Removed unused import

* Added provider function GetPodFullName + ACI implementation

* Added error handling in ACI provider exec

vendor/github.com/docker/spdystream/handlers.go

@@ -0,0 +1,38 @@
+package spdystream
+
+import (
+	"io"
+	"net/http"
+)
+
+// MirrorStreamHandler mirrors all streams.
+func MirrorStreamHandler(stream *Stream) {
+	replyErr := stream.SendReply(http.Header{}, false)
+	if replyErr != nil {
+		return
+	}
+
+	go func() {
+		io.Copy(stream, stream)
+		stream.Close()
+	}()
+	go func() {
+		for {
+			header, receiveErr := stream.ReceiveHeader()
+			if receiveErr != nil {
+				return
+			}
+			sendErr := stream.SendHeader(header, false)
+			if sendErr != nil {
+				return
+			}
+		}
+	}()
+}
+
+// NoopStreamHandler does nothing when stream connects, most
+// likely used with RejectAuthHandler which will not allow any
+// streams to make it to the stream handler.
+func NoOpStreamHandler(stream *Stream) {
+	stream.SendReply(http.Header{}, false)
+}