Initial c style parser in cpp for http headers
* Trying to learn the 'right way' to build a parser
* This is certainly not it, yet
* Thought I would go for more of a c style approach to start
* Then look at it in the context of cpp style containers (stringstream?)
* Barely even shows up in profile (0.6%) -- 15k req/s still
* Needs a data structure to hold the request header data
* method, path, upgrade, arbitrary property bag of header fields
* This should probably go on the free store -- parser won't live forever
* This parser is in no way strict, doesn't handle partial requests
Factor headers into its own class
* Try and understand the cost to new up an object that you might want to
  last longer than the receive call
* Turns out that unordered_map and string hashes are expensive
* If we don't need O(1) lookup, probably much better to store in a
  regular map which uses a tree for storage and isn't as expensive
* Switch over to initialization lists for POD