Add CI for Boost 1.55 and 1.56
Workaround Boost.Optional 1.56.0 MSVC 2010 Issue

This change takes the advice of the Boost.Optional maintainer when
working around the breaking changes in Boost.Optional 1.56.0 --
apparently MSVC has a bug in copy-construction resolution which
considers multiple conversions (not a standard-conforming extension)
and because of changes to the Boost.Optional interface is being hit.

This commit only works around the MSVC 2010 compiler. It may be that
the bug is also in newer versions of the compiler, but that I'm less
sure about.
Apparently 1.56.0 is not supported yet
Enable workaround for higher versions of MSVC.
Merge pull request #439 from deanberris/0.11-devel-travis-newboosts

Add CI for Boost 1.55 and 1.56
Removes trailing white spaces.
Fixes HTTP response status wrapper reference.
Removes trailing white space.
Removes trailing white spaces.
Fixes sphinx 'note' and 'warning' directive formatting.
Replaces tabs with spaces in HTTP client example.
Updates generated HTML documentation.
Merge pull request #441 from povilasb/0.11-devel-docfix-http-response-status

0.11 devel docfix http response status