Add common "form poster" logic, to make CSRF token/header names configurable

also refactor the Feedback logic to use it

tailbone/static/themes/falafel/js/tailbone.feedback.js

@@ -2,6 +2,7 @@
 let FeedbackForm = {
     props: ['action', 'message'],
     template: '#feedback-template',
+    mixins: [FormPosterMixin],
     methods: {
 
         showFeedback() {
@@ -20,30 +21,11 @@ let FeedbackForm = {
                 message: this.message.trim(),
             }
 
-            let headers = {
-                // TODO: should find a better way to handle CSRF token
-                'X-CSRF-TOKEN': this.csrftoken,
-            }
-
-            this.$http.post(this.action, params, {headers: headers}).then(({ data }) => {
-                if (data.ok) {
-                    alert("Message successfully sent.\n\nThank you for your feedback.")
-                    this.showDialog = false
-                    // clear out message, in case they need to send another
-                    this.message = ""
-                } else {
-                    this.$buefy.toast.open({
-                        message: "Failed to send feedback:  " + data.error,
-                        type: 'is-danger',
-                        duration: 4000, // 4 seconds
-                    })
-                }
-            }, response => {
-                this.$buefy.toast.open({
-                    message: "Failed to send feedback!  (unknown server error)",
-                    type: 'is-danger',
-                    duration: 4000, // 4 seconds
-                })
+            this.submitForm(this.action, params, response => {
+                alert("Message successfully sent.\n\nThank you for your feedback.")
+                this.showDialog = false
+                // clear out message, in case they need to send another
+                this.message = ""
             })
         },
     }