Minor grammar correction in error message

Fix grammar in the display message when the `pgo` client receives a 405 error from the API server.

Author: abrightwell

pgo/api/common.go

@@ -28,7 +28,7 @@ func StatusCheck(resp *http.Response) error {
 if resp.StatusCode == 401 {
 return fmt.Errorf("Authentication Failed: %d\n", resp.StatusCode)
 } else if resp.StatusCode == 405 {
-return fmt.Errorf("Method %s for URL %s is not allowed in current the Operator "+
+return fmt.Errorf("Method %s for URL %s is not allowed in the current Operator "+
 "install: %d", resp.Request.Method, resp.Request.URL.Path, resp.StatusCode)
 } else if resp.StatusCode != 200 {
 return fmt.Errorf("Invalid Status Code: %d\n", resp.StatusCode)