WIP: Using stand-alone Asio with C++11

Removing dependency on Boost.Asio and using the standalone Asio version.
fix uri decoding and query string parsing
Allow co-located Xcode builds.

I'm adding the generated CMake artefacts to .gitignore so that Xcode
users who choose to self-host on the same development directory can do
so.
Lining up message's get_body

Clang found some hidden virtual functions in message_base. This commit
fixes the warnings.
Revert "Lining up message's get_body"

This reverts commit 38fcd3a64432c870a0812e0515114256d2a626ea.
Revert "Revert "Lining up message's get_body""

This reverts commit 47bf918071839089d129bea23680b00775356a57.
Missed changes to the message_base type.
Add move constructor and assignment for client_options.

Untested, but should allow in-place definition of client_options in the
client constructor.
Missed change to request_base.hpp

Required follow-up to message_base changes.
Merge branch 'master' of git://github.com/cpp-netlib/cpp-netlib into cpp-netlib-master

Conflicts:
	.gitignore
Re-indent with Xcode.

Prepare for further changes.
CMake changes to support Xcode and Apple's Clang

This change should make Xcode and Apple's Clang builds with CMake
actually work. The recommended generator pattern is:

  BOOST_ROOT=… cmake -G"Xcode" -DCMAKE_CXX_COMPILER=clang++
Request/Reponse changes to follow message_base changes.
Remove explicit call to std::move on std::string.
Update thread_pool to use std::thread instead of boost::thread.
Merge pull request #10 from cpp-netlib/master

Sync from cpp-netlib/cpp-netlib.
Merge branch 'master' into cleanup/use-std

Conflicts:
	CMakeLists.txt
	include/network/message/message.hpp
	include/network/message/message.ipp
	include/network/message/message_base.hpp
	include/network/protocol/http/client/connection/async_normal.ipp
	include/network/protocol/http/client/options.hpp
	include/network/protocol/http/client/options.ipp
	include/network/protocol/http/request/request.hpp
	include/network/protocol/http/request/request_base.hpp
	include/network/protocol/http/response/response.hpp
	include/network/utils/thread_pool.hpp
	include/network/utils/thread_pool.ipp
Builds with std::* and Boost.Asio

Changes to use std:: version of some Boost libraries. Currently this
builds with Boost.Asio even in C++11 mode. We'll use standalone Asio in
C++11 mode another day.
std'ification of <thread> and internal API changes

This change should get the message implementations to a state where it
should be buildling.
Continuation of std'ification.

I've run into some issues with Boost.Test ToT with Apple's Clang
compiler (4.5). It seems that the way Boost.Test is using preprocessor
programming is undesirable to Clang.