chore: integrating .travis.yml fixes from master

.travis.yml

@@ -45,12 +45,20 @@ after_success:
        [ "$TRAVIS_REPO_SLUG" == "lhorie/mithril.js" ]
     then
       # Generate docs
-      $(npm-bin) run gendocs
+      npm run gendocs
       
+      # Set up git env
+      git config --global user.email "$GH_USER_EMAIL"
+      git config --global user.name "$GH_USER_NAME"
+
       # Commit docs to gh-pages branch
       # Using --add to ensure that archived versions aren't lost
       # Using --repo to force it to go over SSH so the saved keys are used (tschaub/gh-pages#160)
-      $(npm bin)/gh-pages --dist ./dist --add --repo "git@github.com:lhorie/mithril.js.git"
+      $(npm bin)/gh-pages \
+        --dist ./dist \
+        --add \
+        --repo "git@github.com:lhorie/mithril.js.git" \
+        --message "Generated docs for commit $TRAVIS_COMMIT [skip ci]"
     else
       echo "Not submitting documentation updates"
     fi