Travis CI: Update Go version, add tip
Travis CI: Update Go version, add tip

arithmetric/restic,fawick/restic,bchapuis/restic,jayme-github/restic,restic/restic,middelink/restic,restic/restic,ckemper67/restic,mappu/restic,middelink/restic,ar-jan/restic,jayme-github/restic,stuertz/restic,ar-jan/restic,kurin/restic,stuertz/restic,fawick/restic,byo/restic,kurin/restic,byo/restic