C++ Network Library Code

Merging from urllib-dean r205.

Implementing tag-based dispatching for string type deduction in the hostname parser.

Test and supporting implementation for invalid formatted hostnames.

Integrating URI implementation to be used in HTTP request message.

Adding network client and server hints.

Using Boost.Spirit classic includes and namespace.

Cleanup of http message test, removing redundant namespace using declarations.

Refactoring fixtures.

I managed to update the unit tests for boost::network::message and boost::network::uri ... this is works and also applies for std::wstring. However, I've had to update the directives in order to make this work... we need to return to this because it's not generic. But it works, and it's a measurable improvement (we had no tests for std::wstring before).

One final test is to define a fake string & ostringstream that can verify that boost::network::basic_message is genuinely generic.

Furthermore, URI tests were update, and basic URI works with std::wstring. However, boost::network::http doesn't support wstring at all yet (neither URI nor message).