Tweak travis config

.travis.yml

@@ -1,22 +1,21 @@
 language: rust
-rust:
-  - stable
-  - beta
-  - nightly
-sudo: false
-before_script:
-  - pip install 'travis-cargo<0.2' --user && export PATH=$HOME/.local/bin:$PATH
+matrix:
+  include:
+    - rust: stable
+    - rust: beta
+    - rust: nightly
+    - rust: nightly
+      script: cargo doc --no-deps
+      deploy:
+        provider: pages
+        skip-cleanup: true
+        github-token: $GITHUB_TOKEN
+        keep-history: true
+        on:
+          branch: master
 script:
   - cargo build --verbose
   - cargo test --verbose
-  - cargo doc --no-deps
-after_success:
-  - travis-cargo --only nightly doc-upload
-env:
-  global:
-    secure: "TyMGH+sbPmKs9lKCziKShxWr3G6im0owEchVrbUChWnQIQv1WydXftFoEoUsVl6qZspjehWK1b1AsnIgCXK0HtEi4DnqLsxs0s36bOjfg5yHBT/pETTr6kcq7KAL4Be4GmI331k6gT1Oi0TPFp7Sg9xpiWsQqKIHA5Szk2wpFQ8="
-
-
 notifications:
   email:
     on_success: never