SSL configuration on rubygems.org has numerous security problems

The SSL configuration on rubygems.org has a number of problems with its current setup:

* Vulnerable to BEAST attack
* Anonymous ciphers enabled
* Extremely weak ciphers enabled

https://www.ssllabs.com/ssltest/analyze.html?d=rubygems.org currently gives https://rubygems.org a score of 'F'.

Considering how many people download gems from rubygems.org, would be nice for it to not be vulnerable to various SSL-related problems. As such, I've made some modifications to the nginx balancer config to address these issues, as well as some other issues I noticed.