- Added the application feature - a big reason why Lean was created in the first place.

- Began moving some repetitive parts from projects to projects into lean

meta/i18n/en/lean.error.json

@@ -0,0 +1,9 @@
+{
+  "404": {
+    "title": "Page not found",
+    "page-title": "404 - Page not found",
+    "subtitle": "You may have followed an invalid or expired link...",
+    "message": "It seems like an error occured on the link you visited / action you tried. A notification was sent to the application's developer.",
+    "back": "Return to previous page"
+  }
+}