Conver to regular Go vendor + dep tool

vendor/github.com/cheggaaa/pb/pb_appengine.go

@@ -0,0 +1,11 @@
+// +build appengine
+
+package pb
+
+import "errors"
+
+// terminalWidth returns width of the terminal, which is not supported
+// and should always failed on appengine classic which is a sandboxed PaaS.
+func terminalWidth() (int, error) {
+	return 0, errors.New("Not supported")
+}