(PUP-1283) win32-security gem raises a different exception

Previously, puppet relied on win32-security version 0.1.4, which raised
Win32::Security::SID::Error when it failed to resolve a name into a SID.

Newer FFI versions of win32-security raise SystemCallError instead,
which is a StandardError subclass. When trying to run the puppet agent
against newer versions of the library, puppet reports:

    Uninitialized constant Win32::Security::SID::Error

This commit changes the rescue to capture SystemCallError instead. This
exception is defined in ruby 1.8.7 and up.
(maint) Eliminate duplicate constant warning

Previously, when executing specs on Windows the following warning would be
displayed:

    warning: already initialized constant FILE

This commit updates the spec test so it doesn't define a top level constant
Merge branch 'ticket/master/PUP-1283-bump-win32-security'

* ticket/master/PUP-1283-bump-win32-security:
  (maint) Eliminate duplicate constant warning
  (PUP-1283) win32-security gem raises a different exception
Merge branch 'master' of https://github.com/puppetlabs/puppet