Removed Node versions that are no longer supported (see https://githu…

…b.com/nodejs/Release)

.travis.yml

@@ -12,20 +12,16 @@ addons:
 matrix:
   include:
     # Local Browsers
-    - node_js: 9
+    - node_js: 10
       env: KARMA=true KARMA_COVERAGE=true
 
     # Sauce Labs
-    - node_js: 9
+    - node_js: 10
       env: KARMA=true KARMA_SAUCE=true
 
     # Node
-    - node_js: 4
-    - node_js: 5
     - node_js: 6
-    - node_js: 7
     - node_js: 8
-    - node_js: 9
 
 before_script:
   # Setup a virtual display for browser testing