Maint: Fix miscellaneous tests

Several tests were broken due to pecularities of Windows
and Ruby on Windows:

• Ruby on windows does not differentiate between group and other file permissions.
• All open file handles must be closed before the file can be deleted
• Sometimes the current working directory (Dir.getwd) is reported as C:/foo and other times as C:\\foo, which confuses the spec tests.
• Ruby's sprintf formats floating point values differently on Windows vs Unix. The Windows exponent has an extra leading zero.
• Needed to stub execution of security command with the SMF service provider.

Reviewed-by: Jacob Helwig <jacob@puppetlabs.com>