Added Remove-NSSystemFile, Get-NSHardware and corrected Get-NSSystemFile

[dbroeglin]

Related Issue

1. Added Remove-NSSystemFile: #69
2. Added Get-NSHardware: #70
3. Corrected a bug in Get-NSSystemFile: #71

Motivation and Context

Those functions are needed for housekeeping (automating setup, cleaning up NS after between tests, allow for system file changes or simply removing unused files)

Also corrected a typo in Install-NSLicense.

How Has This Been Tested?

Tested in my local lab (NS 11.1 48.10). See https://github.com/dbroeglin/windows-lab

On PS v6.0 MacOSX and PS v5.1 on Windows Server 2016

Types of changes

• [x] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [] Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• [x] My code follows the code style of this project.
• [ ] My change requires a change to the documentation.
• [x] I have updated the documentation accordingly.
• [x] I have read the CONTRIBUTING document.
• [ ] I have added tests to cover my changes.
• [x] All new and existing tests passed.

[devblackops]

Looks good to me. Thanks!