provisional: Attachments now uses base64 padding not raw mode (#629)

* corrected base64 encoding of attachments to use padding as that's what cuke JVM does

Author: Johnlon

internal/formatters/fmt_cucumber.go

@@ -308,7 +308,7 @@ func (f *Cuke) buildCukeStep(pickle *messages.Pickle, stepResult models.PickleSt
 		for _, a := range stepResult.Attachments {
 			attachments = append(attachments, cukeEmbedding{
 				Name:     a.Name,
-				Data:     base64.RawStdEncoding.EncodeToString(a.Data),
+				Data:     base64.StdEncoding.EncodeToString(a.Data),
 				MimeType: a.MimeType,
 			})
 		}

internal/formatters/formatter-tests/cucumber/scenario_with_attachment

@@ -30,12 +30,12 @@
                             {
                                 "name": "TheFilename1",
                                 "mime_type": "text/plain",
-                                "data": "VGhlRGF0YTE"
+                                "data": "VGhlRGF0YTE="
                             },
                             {
                                 "name": "TheFilename2",
                                 "mime_type": "text/plain",
-                                "data": "VGhlRGF0YTI"
+                                "data": "VGhlRGF0YTI="
                             }
                         ]
                     },
@@ -54,12 +54,12 @@
                             {
                                 "name": "TheFilename1",
                                 "mime_type": "text/plain",
-                                "data": "VGhlRGF0YTE"
+                                "data": "VGhlRGF0YTE="
                             },
                             {
                                 "name": "TheFilename2",
                                 "mime_type": "text/plain",
-                                "data": "VGhlRGF0YTI"
+                                "data": "VGhlRGF0YTI="
                             }
                         ]
                     }