Set git committer single-use vars

/ht @cwillisf

Author: Ray Schamp

.travis.yml

@@ -29,7 +29,5 @@ after_script:
     npm --no-git-tag-version version $($(npm bin)/json -f package.json version)-prerelease.$(date +%s)
     npm publish
     # Publish to gh-pages as most recent committer
-    git config --global user.email $(git log --pretty=format:"%ae" -n1)
-    git config --global user.name $(git log --pretty=format:"%an" -n1)
-    npm run --silent deploy -- -x -r https://${GH_TOKEN}@github.com/${TRAVIS_REPO_SLUG}.git
+    GIT_AUTHOR_EMAIL=$(git log --pretty=format:"%ae" -n1) GIT_AUTHOR_NAME=$(git log --pretty=format:"%an" -n1) npm run --silent deploy -- -x -r https://${GH_TOKEN}@github.com/${TRAVIS_REPO_SLUG}.git
   fi