bpardee-net-http-persistent

This is an experimental branch that implements a connection pool of Net::HTTP objects instead of a connection/thread. C/T is fine if you're only using your http threads to make connections but if you use them in child threads then I suspect you will have a thread memory leak. Also, I want to see if I get less connection resets if the most recently used connection is always returned. Also added a :force_retry option that if set to true will retry POST requests as well as idempotent requests. This branch is currently incompatible with the master branch in the following ways: * It doesn't allow you to recreate the Net::HTTP::Persistent object on the fly. This is possible in the master version since all the data is kept in thread local storage. For this version, you should probably create a class instance of the object and use that in your instance methods. * It uses a hash in the initialize method. This was easier for me as I use a HashWithIndifferentAccess created from a YAML file to define my options. This should probably be modified to check the arguments to achieve backwards compatibility. * The method shutdown is unimplemented as I wasn't sure how I should implement it and I don't need it as I do a graceful shutdown from nginx to finish up my connections. For connection issues, I completely recreate a new Net::HTTP instance. I was running into an issue which I suspect is a JRuby bug where an SSL connection that times out would leave the ssl context in a frozen state which would then make that connection unusable so each time that thread handled a connection a 500 error with the exception "TypeError: can't modify frozen". I think Joseph West's fork resolves this issue but I'm paranoid so I recreate the object. Compatibility with the master version could probably be achieved by creating a Strategy wrapper class for GenePool and a separate strategy class with the connection/thread implementation.