Travis CI: Use Node.js 5 instead of stable
Travis CI: Use Node.js 5 instead of stable

Refs https://github.com/twbs/grunt-bootlint/pull/61
2947721120/ubiquitous-octo-kumquat,freezy-sk/bootlint,chrismbarr/bootlint,twbs/bootlint,chrismbarr/bootlint,2947721120/ubiquitous-octo-kumquat,chrismbarr/bootlint,freezy-sk/bootlint,freezy-sk/bootlint,twbs/bootlint,2947721120/ubiquitous-octo-kumquat