Implement changes from PR in order to get tests passing

https://github.com/DusanKasan/parsemail/pull/5/files
diff --git a/parsemail_test.go b/parsemail_test.go
index e0457bb..809aad8 100644
--- a/parsemail_test.go
+++ b/parsemail_test.go
@@ -248,11 +248,7 @@
 	}
 
 	for index, td := range testData {
-		m, err := mail.ReadMessage(strings.NewReader(td.mailData))
-		if err != nil {
-			t.Error(err)
-		}
-		e, err := Parse(m)
+		e, err := Parse(strings.NewReader(td.mailData))
 		if err != nil {
 			t.Error(err)
 		}