build: run lint on all compatible Node.js builds

Author: dougwilson

.travis.yml

@@ -29,7 +29,7 @@ before_install:
   # Setup Node.js version-specific dependencies
   - "test $TRAVIS_NODE_VERSION != '0.6' || npm rm --save-dev istanbul"
   - "test $TRAVIS_NODE_VERSION != '0.8' || npm rm --save-dev istanbul"
-  - "test $TRAVIS_NODE_VERSION  = '4.7' || npm rm --save-dev eslint"
+  - "test $(echo $TRAVIS_NODE_VERSION | cut -d. -f1) -ge 4 || npm rm --save-dev eslint"
 
   # Update Node.js modules
   - "test ! -d node_modules || npm prune"