SystemInformation: Report more information

Support probing of the current process memory usage in KB
(linux,win,mac), the total physical memory in KB (linux,win,mac), and
the model name field of the cpuinfo (Linux only).  Add a method to
return the host's FQDN (non-AIX), and methods to test for OS type
(Windows, Apple, Linux).

Change-Id: Iedb238f4ca49d5f13385a71a592ec67cec73b29c