Release 0.9.0.

cpp-netlib v0.9-beta

Point release for 0.8 line: 0.8.1

Changes:
* Adding an overload to connection::write(...) that takes a Boost.Asio const_buffer
  sequence and a completion callback.
* Fix for connection::write_first_line() with potential for crash
* Fixed broken connection::read() implementation
* Fix HTTP header parsing for async_server

Releasing 0.8 finally!

Updating documentation to 0.8.

Merge branch '0.7-devel' of github.com:mikhailberis/cpp-netlib

Adding the correct switch for transform_attribute on the version of s…

…pirit.

Adding MIME library tests to the repository.

Release tag for cpp-netlib 0.5.