Update node version specificity of "4"

RobLoach · RobLoach · commit ec2ab26de0b5 · 2015-09-08T20:54:31.000-04:00
diff --git a/.travis.yml b/.travis.yml
@@ -4,7 +4,7 @@ sudo: false
 node_js:
   - "0.10"
   - "0.12"
-  - "4.0"
+  - "4"
   - "iojs"
 
 after_success:
