Add null character to default gremlins

[wulfsolter]

Description

Add null character to defaults

Motivation and Context

Closes issue #109
Null chars break text files in bash and other languages. Every time I reinstall vscode-gremlins I have to re-add this rule.

How Has This Been Tested?

Open file, see null gremlin, smile :)

Screenshots (if appropriate):

Types of changes

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

Checklist:

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