Fix Travis website deployment (#2274)

Summary:
**Summary**

Sorry I messed up the deployment commands for the new website. SSH mode should not be used.

**Test Plan**

Can't really test locally (or rather, troublesome to test Travis configs locally). Can we try to land it?
Pull Request resolved: #2274

Reviewed By: claudiopro

Differential Revision: D18807347

Pulled By: yangshun

fbshipit-source-id: 82c8bfa0565a4328315ae89bd23bd1d2d6e43a62

.travis.yml

@@ -49,7 +49,7 @@ script:
       git config --global user.name "Travis CI"
       git config --global user.email "travis@reactjs.org"
       echo "machine github.com login reactjs-bot password $GITHUB_TOKEN" > ~/.netrc
-      cd website && yarn install && GIT_USER=reactjs-bot USE_SSH=true yarn deploy
+      cd website && yarn install && GIT_USER=reactjs-bot yarn deploy
     else
       # Make sure the website builds without error
       cd website && yarn install && yarn build