Add node 8 to travis CI
Add node 8 to travis CI

We support node 8 now, so this patch adds it to the CI process.

Signed-off-by: Antoine Tremblay <715cbffe391b68f717536227958c7c21fbce8317@ericsson.com>

lmcgupe/theia,hexa00/theia,hexa00/theia,epatpol/theia-1,epatpol/theia-1,lmcgupe/theia,epatpol/theia-1