add travis

.travis.yml

@@ -0,0 +1,15 @@
+after_success: |
+  if [ -n "$GITHUB_API_KEY" ]; then
+    cd "$TRAVIS_BUILD_DIR"
+    # This generates a `web` directory containing the website.
+    make web
+    cd web
+    git init
+    git checkout -b gh-pages
+    git add .
+    git -c user.name='travis' -c user.email='travis' commit -m init
+    # Make sure to make the output quiet, or else the API token will leak!
+    # This works because the API key can replace your password.
+    git push -f -q https://<me>:$GITHUB_API_KEY@github.com/<me>/<myrepo>-gh-pages gh-pages &2>/dev/null
+    cd "$TRAVIS_BUILD_DIR"
+  fi