Update .travis.yml

Bring travis in to alignment with guides.

.travis.yml

@@ -5,10 +5,11 @@ script:
 - mkdocs build --verbose --clean
 deploy:
  provider: pages
+ keep-history: true
  skip_cleanup: true
  github_token: $GITHUB_TOKEN
  local_dir: site
- name: $BOT_NAME
- email: $BOT_EMAIL
+ committer-from-gh: true
+ verbose: true
  on:
    branch: master