(CFACT-104) fix segv for dmi facts solaris

Previously, dmi facts relied on the architecture fact being resolved, and
was using the value without checking whether it was resolved or not. This
resulted in core dumps when the fact was not resolved.

This patch incorporates a null check to make sure that it does not core
dump.
Merge pull request #142 from vrthra/fix/cfact-104/dmi-solaris

(CFACT-104) fix segv for dmi facts solaris
(CFACT-91) Add Windows external fact infrastructure.

Add some external fact support, with framework for executables.
New to Windows are batch files and Powershell scripts.
Partial implementation of process execution
Add link for redirecting input/output with CreateProcess