Test: Update npm to v4 when nodejs is v5 because of npm install error.

Author: sttk

.travis.yml

@@ -17,6 +17,11 @@ node_js:
   - '0.12'
   - '0.10'
 
+before_install:
+  - if [ $(echo "${TRAVIS_NODE_VERSION}" | cut -d'.' -f1) -eq 5 ]; then
+      npm i -g npm@4;
+    fi
+
 after_success:
   - if [ $(echo "${TRAVIS_NODE_VERSION}" | cut -d'.' -f1) -ge 6 ]; then
       npm run coveralls;

appveyor.yml

@@ -20,7 +20,8 @@ environment:
 
 install:
   - ps: Install-Product node $env:nodejs_version
-  - npm install
+  - ps: if ($env:nodejs_version -eq '5') { npm i -g npm@4 }
+  - cmd: npm install
 
 test_script:
   - node --version