Enable yarn caching in .travis.yml (#639)

wbreakell · timdorr · commit ff33f0ccce44 · 2017-03-03T12:58:46.000-05:00
diff --git a/.travis.yml b/.travis.yml
@@ -6,3 +6,4 @@ script:
   - npm run test:cov
 after_success:
   - npm run coverage
+cache: yarn
