Use Ructe (#327)

All the template are now compiled at compile-time with the `ructe` crate.

I preferred to use it instead of askama because it allows more complex Rust expressions, where askama only supports a small subset of expressions and doesn't allow them everywhere (for instance, `{{ macro!() | filter }}` would result in a parsing error).

The diff is quite huge, but there is normally no changes in functionality.

Fixes #161 and unblocks #110 and #273

src/api/apps.rs

@@ -1,5 +1,5 @@
 use canapi::Provider;
-use rocket_contrib::Json;
+use rocket_contrib::json::Json;
 use serde_json;
 
 use plume_api::apps::AppEndpoint;
@@ -10,7 +10,7 @@ use plume_models::{
 };
 
 #[post("/apps", data = "<data>")]
-fn create(conn: DbConn, data: Json<AppEndpoint>) -> Json<serde_json::Value> {
+pub fn create(conn: DbConn, data: Json<AppEndpoint>) -> Json<serde_json::Value> {
     let post = <App as Provider<Connection>>::create(&*conn, (*data).clone()).ok();
     Json(json!(post))
 }