Alter tested nodejs environments
Alter tested nodejs environments

Only test with using long-time-support nodejs environments [0].

We shift to 4.4 and 6.1, which are available on TravisCI [1].

[0] https://github.com/nodejs/LTS#lts-schedule
[1] https://docs.travis-ci.com/user/languages/javascript-with-nodejs#Available-Versions

CCI-MOC/GUI-Frontend,CCI-MOC/GUI-Frontend,CCI-MOC/GUI-Frontend,CCI-MOC/GUI-Frontend,CCI-MOC/GUI-Frontend