Move handlebars helper to its own file

src/handlebars_util.rs

@@ -0,0 +1,13 @@
+use rocket_contrib::templates::Engines;
+use handlebars::handlebars_helper;
+
+pub fn register_helpers(engines: &mut Engines) {
+    handlebars_helper!(pretty_datetime: |dt: str| {
+        let date = dt.trim_end_matches(|c| c != 'T').trim_end_matches('T');
+        let time = dt.trim_start_matches(|c| c != 'T').trim_start_matches('T')
+            .trim_end_matches(|c| c != ':').trim_end_matches(':');
+        format!("{} {}", date, time)
+    });
+
+    engines.handlebars.register_helper("pretty_datetime", Box::new(pretty_datetime));
+}