add linter command

.travis/push.sh

@@ -1,5 +1,3 @@
-#!/bin/sh
-
 setup_git() {
   git config --global user.email "travis@travis-ci.org"
   git config --global user.name "Travis CI"
@@ -8,6 +6,11 @@ setup_git() {
 commit_website_files() {
   git checkout master
   git add *
+  if [[ $(( $TRAVIS_BUILD_NUMBER % 5 )) == 0 ]]; then
+      n = $(( ($TRAVIS_BUILD_NUMBER-270)/5))
+      npm run linter
+      echo "Linting build:  $n"
+  fi
   git commit --message "Travis build: $TRAVIS_BUILD_NUMBER"
 }