recipe/upgrade: Add non-interactive mode.

Add support for -n which just outputs the list of compatible tags for each image.

cli/recipe/upgrade.go

@@ -240,15 +240,21 @@ You may invoke this command in "wizard" mode and be prompted for input:
 							compatibleStrings = append(compatibleStrings, regVersion)
 						}
 					}
-
-					prompt := &survey.Select{
-						Message: msg,
-						Help:    "enter / return to confirm, choose 'skip' to not upgrade this tag, vim mode is enabled",
-						VimMode: true,
-						Options: compatibleStrings,
-					}
-					if err := survey.AskOne(prompt, &upgradeTag); err != nil {
-						logrus.Fatal(err)
+					if internal.NoInput {
+						logrus.Infof("potential upgrades for service: %s, image: %s, tag: %s ::\t", service.Name, image, tag)
+						for _, upgradableVersion := range compatibleStrings[1:] {
+							logrus.Infof("\t%s\n", upgradableVersion)
+						}
+					} else {
+						prompt := &survey.Select{
+							Message: msg,
+							Help:    "enter / return to confirm, choose 'skip' to not upgrade this tag, vim mode is enabled",
+							VimMode: true,
+							Options: compatibleStrings,
+						}
+						if err := survey.AskOne(prompt, &upgradeTag); err != nil {
+							logrus.Fatal(err)
+						}
 					}
 				}
 			}