feat: sanitize HTML in footer

moved sanitize function into a separate file including some simple tests

closes #91

src/sanitize.ts

@@ -0,0 +1,15 @@
+import sanitizeHtml from 'sanitize-html';
+
+const defaultSanitizeOptions = {
+  allowedTags: ['b', 'i', 'em', 'strong', 'a', 'ul', 'ol', 'li'],
+  allowedAttributes: {
+    'a': ['href', 'target']
+  }
+}
+
+export const sanitize = (dirty: string, options: sanitizeHtml.IOptions = defaultSanitizeOptions) => ({
+  __html: sanitizeHtml(
+    dirty,
+    options
+  )
+});