Add Node.js 6 LTS to CI

.travis.yml

@@ -2,6 +2,7 @@ language: node_js
 
 node_js:
   - 'stable'
+  - '6'
   - '4'
 
 sudo: false

netci.groovy

@@ -5,7 +5,7 @@ import jobs.generation.Utilities;
 def project = GithubProject
 def branch = GithubBranchName
 
-def nodeVersions = ['stable', '4']
+def nodeVersions = ['stable', '6', '4']
 
 nodeVersions.each { nodeVer ->