Remove Canapi (#540)

* Remove Canapi

It added more complexity than it helped.

* Fail if there are many blog, but none was specified

* cargo fmt

plume-api/src/lib.rs

@@ -1,24 +1,6 @@
-extern crate canapi;
 extern crate serde;
 #[macro_use]
 extern crate serde_derive;
 
-macro_rules! api {
-    ($url:expr => $ep:ty) => {
-        impl Endpoint for $ep {
-            type Id = i32;
-
-            fn endpoint() -> &'static str {
-                $url
-            }
-        }
-    };
-}
-
 pub mod apps;
 pub mod posts;
-
-#[derive(Default)]
-pub struct Api {
-    pub posts: posts::PostEndpoint,
-}