Add & operator for applying hook chains in reverse

Also includes:

- Switch to spago.
- Reimplement ResetToken as a String -- same behavior but easier to debug,
and allows tokens to be used with `show` for use as React keys.

Author: maddie927

Diff for: .travis.yml

@@ -9,7 +9,7 @@ cache: npm
 
 install:
   - npm ci
-  - npx bower i
+  - npx spago install
 
 script:
-  - npx pulp build
+  - npx spago build