C++ Network Library Code

Adding swap support for network::message.

Simplifying message interface, removing mutable and const methods, adding unit test for copy construction, and setting the default path to '/' in case the URI is not explicitly defined in the http::request constructor - (ex. 'http://boost.org/' instead of 'http://boost.org/').

Refactored message declaration to message_fwd.hpp; Updated most files so that they now compile when using gcc's pedantic flag.

Adding support for multi-line header responses.

Adding remove_header directive implementation.

Note: Explore using CRTP/PBCP to directives and hide the message interface from the public?

Adding default User-Agent header in case a User-Agent header doesn't already exist in the request object. I also moved the test for the correct construction of an http request to http_message_test.cpp from http_1_0_test.cpp.

Note: No unit test implemented for this feature; should be doable in the Python CGI script.

Updated documentation.

Fixes for building on GCC 4.2.3 in Ubuntu.

Changes
- Using correct string traits to get the correct type for the string to use based on the tag.
- Using safe(r) string processing methods for handling header lines from the HTTP response.
- basic_response<> now contains version(), status(), and status_message().

TODO:
- multi-line headers processing
- multi-part message posting
- change from multi-map to vector to preserve request header ordering?

Using Boost.Range for iterator ranges instead of a plain pair of integers.