upgrade deps

Both a "cargo update" and a bump of major versions of a few deps.
I left a few alone:

* base64 because some of the deps depend on 0.11 (and 0.9), so I don't
  want to pull in a third version (0.12).
* ring because libpasta depends on this version and I don't want to pull
  in two of them.
* time because it's not trivial. Last I checked, time 0.2 couldn't even
  do what I wanted at all.

I also made tokio use parking_lot, since I pull it in anyway.

src/main.rs

@@ -112,7 +112,7 @@ fn main() {
         .build();
     h.clone().install().unwrap();
 
-    if let Err(e) = { let _a = h.r#async(); args.run() } {
+    if let Err(e) = { let _a = h.async_scope(); args.run() } {
         error!("{:?}", e);
         ::std::process::exit(1);
     }