Update Heroku feature set

This chart update is based on these test results for tickets and forward secrecy:

https://www.ssllabs.com/ssltest/analyze.html?d=dashboard.heroku.com&s=50.19.233.212

I'm unsure if these results indicate anything else should become green. (It doesn't appear that OCSP stapling and APN are supported yet)
Merge pull request #33 from csuhta/patch-1

Update Heroku feature set