extract interfaces, multiple apps support

This is the first commit. New interfaces for WebListener and AppHost were added. 
Communication between Listener and WebServer goes throught AppDomains boundary,
what will bring the ability to support multiple web apps in signle process.
add records to queue before handle them in threadpool
first implementation of native listener
generalizing IWebRequest and IApplicationHost interfaces
added libnative
refactored interfaces 

decoupling transport from ApplicationHost by passing its type
removed hardcoded configuration
added makefiles for native library
added release notes
added xml configuration support

now listener can have custom xml-configurable options. 
To use it, mark the class with attribute  [Config(typeof(YourConfigClass))]
and mark the properties of YourConfigClass with xml serialization attributes
sample config files
added libevent to travis
Merge branch 'interface' of https://github.com/xplicit/HyperFastCgi into interface