travis -- build binaries as a test as well

.travis.yml

@@ -6,7 +6,17 @@ go:
   - master
   - tip
 
+os:
+  - linux
+  - osx
+
+before_install:
+  - if [[ "$TRAVIS_OS_NAME" == "linux" ]]; then curl -o- -L https://yarnpkg.com/install.sh | bash; fi
+  - if [[ "$TRAVIS_OS_NAME" == "linux" ]]; then export PATH="$HOME/.yarn/bin:$HOME/.config/yarn/global/node_modules/.bin:$PATH"; fi
+  - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then brew install yarn; fi
+
 script:
   - cd dnsfilter && go get -d -t . && go test
   - cd ../coredns_plugin && go get -d -t . && go test
+  - cd .. && make