Use 'npm bin' to find the correct binaries

.travis.yml

@@ -15,11 +15,10 @@ before_install:
 - "if [ -d node_modules ] && [ x$(cat node_modules/.last-node-version 2>/dev/null) != x$(node -e 'console.log(process.version)') ]; then npm rebuild && node -e 'console.log(process.version)' > node_modules/.last-node-version; fi"
 before_script:
 - npm install web-component-tester bower polylint
-- bower install
-- polylint --no-recursion
-- export PATH=$PWD/node_modules/.bin:$PATH
+- $(npm bin)/bower install
+- $(npm bin)/polylint --no-recursion
 script:
-- xvfb-run wct
-after_success: '[ ${TRAVIS_PULL_REQUEST} = "false" ] && [ ${TRAVIS_BRANCH} = "master" ] && bower install -s https://${GH_TOKEN}@github.com/Collaborne/collaborne-build-tools.git && bower_components/collaborne-build-tools/gpages_build.sh Collaborne info@collaborne.com'
+- xvfb-run $(npm bin)/wct
+after_success: '[ ${TRAVIS_PULL_REQUEST} = "false" ] && [ ${TRAVIS_BRANCH} = "master" ] && $(npm bin)/bower install -s https://${GH_TOKEN}@github.com/Collaborne/collaborne-build-tools.git && bower_components/collaborne-build-tools/gpages_build.sh Collaborne info@collaborne.com'
 env:
   secure: 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