Adding overload specialization for CreationRules::New

This fixes MSVC, which seems to have a problem when specializing a ctor with a template parameter pack.  To avoid this issue, a no-argument variant is provided.
Adding a unit test to provide justification for prior changes
Merge pull request #43 from leapmotion/bug-msvcvarargs

Adding overload specialization for CreationRules::New
Updating atomic_object documentation
Merge pull request #44 from leapmotion/doc-atomicobject

Updating atomic_object documentation
If EXTERNAL_LIBRARY_DIR is set, we want to add it to our search path
Correcting Boost package search on Windows
Fixing Windows autonet build
Making use of PMPL with the AutoNetServer
Merge pull request #45 from leapmotion/ref-nowebsocketheaders

Remove websocket headers from AutoNetServer.h