async: got rid of code duplication. Removed the Promise<void> specialization and specialized the Core instead

commit e60bcb0bc15fbba453340d69d106c5850b9a6d67
Author: octal <mathieu.stefani@supinfo.com>
Date:   Thu Nov 12 14:14:53 2015 +0100

    Added a NoExcept concept that will call std::terminate if a promise has been rejected

commit bae200046427b93e6f124c848ab36d246a7580c3
Author: octal <mathieu.stefani@supinfo.com>
Date:   Wed Nov 11 14:50:27 2015 +0100

    Updated Optional to be able to move the result out when chaining a Promise

commit da60bc8b02a1fb89a91985a0da9ddf4b7219f5b3
Author: octal <mathieu.stefani@supinfo.com>
Date:   Fri Nov 6 17:43:36 2015 +0100

    Started working on a proof-of-concept implementation of an asynchronous primitive based on the Promises/A+ specification

instead is a shared_ptr

Conflicts:
	src/http.cc

Added a Date and a Raw header. Raw headers will be used when the parser encounters a header that it does not know. Raw headers only store strings for now

The reason is to avoid some headers name like Server or Date to collide
with some other generic classes that might have the same name

Also used the macro when checking if the subtype belongs to the vendor
tree.

Added an ArrayBuf class that provides an array-based streambuf so that response content can now be directly serialized to a fixed-size char buffer with standard iostream interface

The server now returns an HTTP Bad Request when parsing fails and returns a 500 when an exception is thrown

The parser is now associated to a particular connection (peer) so that it can parse a request from multiple tcp packets