Fix nxService crashing when service does not exist

[gurrajatwal]

Pull Request (PR) description

The nxService resource crashes when auditing a service that does not exist. The if statement that was supposed to handle this case had the wrong condition.

This Pull Request (PR) fixes the following issues

• Fixes #30

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] Comment-based help added/updated.
• [x] 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.

[eehret]

@gurrajatwal , @kwirkykat Thank you both for working on this. We are waiting on the release of this fix as well as a number of others, so I'm eager to learn when the next package will be pushed to Powershell Gallery. Do you have a rough idea when the next version might appear there? Thanks again! :)