Update deps.

Author: jdalton

.travis.yml

@@ -58,18 +58,11 @@ before_install:
       fi
       ringo -v
 
-  # Use exact Node version.
   - nvm use $TRAVIS_NODE_VERSION
-
-  # Setup package managers.
-  - npm set loglevel error
-  - npm set progress false
-  - npm i -g yarn
-  - yarn -V
+  - npm i -g npm@^5
 
 install:
-  # Install packages.
-  - yarn
+  - npm i
 
 script:
   - cd test