Fix Team City builds

the & made the nUnit.xml impossible to parse. quick-fixing this. There
is #122 issue for this.
Fix internal module support to work on PowerShell 2

Also fixing the TC build again
Fix Parse-ShouldArgs in PowerShell strict mode

Parse-ShouldArgs now works properly if StrictMode has been enabled, performing bounds checking on the $shouldArgs array before indexing.  It also throws an error if no AssertionMethod was passed (ie, ( | Should ) or ( | Should not )).
Fixes #76