Add travis for doc upload

.travis.yml

@@ -0,0 +1,35 @@
+language: rust
+sudo: false
+
+# run builds for all the trains (and more)
+rust:
+  - stable
+  - beta
+  - nightly
+
+# load travis-cargo
+before_script:
+  - |
+      pip install 'travis-cargo<0.2' --user &&
+      export PATH=$HOME/.local/bin:$PATH
+
+# the main build
+script:
+  - |
+      travis-cargo build &&
+      travis-cargo test &&
+      travis-cargo test -- --release &&
+      travis-cargo bench -- --no-run &&
+      travis-cargo doc
+after_success:
+  # upload the documentation (GH_TOKEN from env)
+  - travis-cargo --only nightly doc-upload
+
+branches:
+  only:
+    - master
+
+env:
+  global:
+    # override the default `--features unstable` used for the nightly branch (optional)
+    - TRAVIS_CARGO_NIGHTLY_FEATURE=""