Travis: updated tidy-html5 installation
Travis: updated tidy-html5 installation

sk-/git-lint,sk-/git-lint,sk-/git-lint,sk-/git-lint,stfp/git-lint,sk-/git-lint,stfp/git-lint,stfp/git-lint,sk-/git-lint,sk-/git-lint,stfp/git-lint,stfp/git-lint,sk-/git-lint,sk-/git-lint,stfp/git-lint,stfp/git-lint