chore(ci): use node 4 instead of 5

Author: filipesilva

.appveyor.yml

@@ -1,6 +1,6 @@
 environment:
   matrix:
-  - nodejs_version: "5.0"
+  - nodejs_version: "4.0"
   - nodejs_version: "6.0"
 
 matrix:

.travis.yml

@@ -2,7 +2,7 @@ dist: trusty
 sudo: required
 language: node_js
 node_js:
-  - "5"
+  - "4"
   - "6"
 os:
   - linux
@@ -30,12 +30,12 @@ matrix:
     - node_js: "6"
       env: NODE_SCRIPT="tests/e2e_runner.js --nightly"
     - os: osx
-      node_js: "5"
+      node_js: "4"
       env: SCRIPT=lint
     - node_js: "6"
       env: SCRIPT=build
     - os: osx
-      node_js: "5"
+      node_js: "4"
       env: SCRIPT=build
     - os: osx
       env: TARGET=mobile SCRIPT=mobile_test