Add deploy task to .travis.yml

[#69707496]
only enable codap support if 'codap=true' is in URL

[#69888066]
Merge branch 'master' into s3-deploy
Remove mathjax library, use CDN instead

[#69671476]

It's used only on two docs pages, while it consists of 30 000 files,
what is killing S3 deploy.
Change production branch from master to s3-deploy-test (it's test)