Implemented proper logging, with support for file logging, timestamp and syslog (this last one is untested)

src/db/models/attachment.rs

@@ -78,11 +78,11 @@ impl Attachment {
                 Ok(_) => break,
                 Err(err) => {
                     if retries < 1 {
-                        println!("ERROR: Failed with 10 retries");
+                        error!("Failed with 10 retries");
                         return Err(err)
                     } else {
                         retries -= 1;
-                        println!("Had to retry! Retries left: {}", retries);
+                        info!("Had to retry! Retries left: {}", retries);
                         thread::sleep(time::Duration::from_millis(500));
                         continue
                     }

src/db/models/user.rs

@@ -180,7 +180,7 @@ impl User {
     pub fn update_uuid_revision(uuid: &str, conn: &DbConn) {
         if let Some(mut user) = User::find_by_uuid(&uuid, conn) {
             if user.update_revision(conn).is_err(){
-                println!("Warning: Failed to update revision for {}", user.email);
+                warn!("Failed to update revision for {}", user.email);
             };
         };
     }