Fixes Bug #114: New-Fixture raises exception when using $pwd directly as -Path parameter.
Restricts parameters to [string] instead of letting powershell decide which datatype to use
Merge branch 'fix_exceptions_in_new-fixture'
New-Fixture standardized

- Accept and resolve paths on input as other cmdlets do.
- Output standard objects.
- Using only Name parameter you can create fixture in the current
directory .
- If file exists Warning is issued.
- Numerous internal amendments to make the function easier to read.
- Adding Tests

- not moving the function out of Pester.psm1 to make the changes easier
to track.
Move New-Fixture out of Pester.psm1

- Moved New-Fixture and Create-File to separate script file
- Discarded Write-UsageForNewFixture. Usage can be looked up by
Get-Help, so inline help becomes the only place to update if interface
changes.
Fix tag filter

Fix the tag filter that I broke. We really need a test for this.
marking the 2.0.4 release