CMBoundaries: Adding support for new boundary types

[NEllis280]

Pull Request (PR) description

This PR adds support for the VPN and IPv6Prefix boundary types to the CMBoundaries resource.

This Pull Request (PR) fixes the following issues

• Fixes #79

Task list

• [x] Added an entry to the change log under the Unreleased section of the file CHANGELOG.md. Entry should say what was changed and how that affects users (if applicable), and reference the issue being resolved (if applicable).
• [x] Resource documentation added/updated in README.md.
• [x] Resource parameter descriptions added/updated in README.md, schema.mof and comment-based help.
• [x] Comment-based help added/updated.
• [ ] Localization strings added/updated in all localization files as appropriate.
• [x] Examples appropriately added/updated.
• [x] Unit tests added/updated. See DSC Community Testing Guidelines.
• [ ] Integration tests added/updated (where possible). See DSC Community Testing Guidelines.
• [x] New/changed code adheres to DSC Community Style Guidelines.

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This change is 

[codecov[bot]]

Codecov Report

Merging #99 (3160b2a) into master (c82e49a) will increase coverage by 0%. The diff coverage is 100%.

@@          Coverage Diff          @@
##           master    #99   +/-   ##
=====================================
  Coverage      98%    98%           
=====================================
  Files          41     41           
  Lines        6134   6137    +3     
=====================================
+ Hits         6043   6046    +3     
  Misses         91     91