(cfact-32) Add a first draft of Extensibility.md
Merge pull request #42 from kylog/doc/add-extensibility-readme

(cfact-32) Add a first draft of Extensibility.md
(maint) Set RPATH for non-default lib install path.

If we're using an install prefix that is not targeting a directory
normally searched by the loader, tell CMake to set an install RPATH to the
directory containing libfacter.so.

Also instructing CMake to add "@rpath/" to the install name of libfacter
when building and installing to a non-default lib directory on OSX.  This
allows libfacter to be loaded from the RPATH for that platform.
Merge pull request #44 from peterhuene/maint/rpath

(maint) Set RPATH for non-default lib install path.
(maint) Add API documentation generation.

Adding support for generating API documents using doxygen.
Updating all source files so that there are no doxygen warnings.
Adding documentation generation to Travis CI to ensure no future
warnings.
Ensuring facter library header files are free from implementation (save
templated types).
Merge pull request #43 from peterhuene/maint/docs

(maint) Add API documentation generation.
(maint) Add API documentation generation.

Adding support for generating API documents using doxygen.
Updating all source files so that there are no doxygen warnings.
Adding documentation generation to Travis CI to ensure no future
warnings.
Ensuring facter library header files are free from implementation (save
templated types).
(maint) Return unique_ptr<T> from make_value.

Instead of returning unique_ptr<value> from the utility function make_value, return unique_ptr<T> instead.
unique_ptr<T> can be safely moved into unique_ptr<value> (where T derives from value).
This makes using array and map values easier.
(maint) Fix domain and fqdn facts when domain resolves to hostname.

In the case where the domain is the same as the hostname, treat it like the domain could not be resolved.
This prevents us from setting the domain and fqdn facts to the same value as the hostname.
Ruby facter returns nil for domain and fqdn facts under this condition.
(CFACT-33) Add dhcp_servers fact for OSX and Linux.

Adding a dhcp_servers fact for OSX and Linux.
Adding logic to discover the primary interface based on routing
information.  We still fall back to first interface with an assigned
address if need be.
(maint) Update example in README to configure log4cxx.

Adding code to example to configure log4cxx.
Without this, users would get a warning from log4cxx.