Upgrade CI servers NodeJS version (#434)

Signed-off-by: Juan Cruz Viotti <jviottidc@gmail.com>

.travis.yml

@@ -2,7 +2,7 @@ language: cpp
 sudo: false
 
 env:
-  - NODE_VERSION="5"
+  - NODE_VERSION="6.1.0"
 os:
   - linux
   - osx

appveyor.yml

@@ -17,12 +17,10 @@ environment:
     npm_config_target: 0.37.6
     npm_config_arch: x64
   matrix:
-    - nodejs_version: 5
+    - nodejs_version: 6.1.0
 
 install:
   - ps: Install-Product node $env:nodejs_version x64
-  - npm -g install npm@2
-  - set PATH=%APPDATA%\npm;%PATH%
   - npm install --build-from-source
   - npm install -g bower
   - bower install