(maint) Fix doc comment copy-paste error.

Looks like the short description for scoped_addrinfo was copied from scoped_descriptor.
Changing it to be "scoped addrinfo".
(maint) Update the behavior of the domain/fqdn facts to match Ruby facter.

Recently Ruby facter was changed so that the fqdn fact would resolve to the hostname
if the domain name was empty.

Our implementation differs by actually resolving the hostname with the default name
server.  When the resolution failed with a "no name" error, we would emit a warning
and not resolve either the domain or fqdn facts.

This commit changes the warning to imply that we failed to resolve the hostname and
that will likely indicate that the fqdn fact is not externally resolvable. We then
default the fqdn fact to the hostname and resolve the domain based on the value
of fqdn.
Merge pull request #55 from peterhuene/facts/fqdn

(maint) Fix resolution of fqdn fact.
(doc) Add a README summary at the top
Merge pull request #56 from kylog/doc/readme

(doc) Add a README summary at the top
(maint) Move Find*.cmake to a `cmake` directory

Local cmake code is typically stored in a directory named
`cmake`. Vendor should be kept to the single purpose of holding
3rd-party libraries.
(maint) Do not use CMake's ExternalProject for vendored stuff

ExternalProject is great when vendoring a library with complex build
requirements, but it has some drawbacks. Specifically, it will ignore
the toolchain file that we use to make CMake find our special compiler
and library builds.

This commit removes ExternalProject, and instead embeds the vendored
libraries as part of the normal CMake build process. For rapidjson
this means pretty much nothing, since it is header-only. For gmock a
minimal CMakeLists.txt is added to build the gmock library and set
some variables for us.

The vendored versions of gmock and rapidjson in this commit are
stripped-down, since both contain a bunch of random stuff that isn't
needed for our build process.
Merge pull request #58 from branan/fixup_vendor

(maint) Reorganize the vendor directory