Update file validators to handle mp3 and rtf formats

[JRD-OneBeyond]

Add mp3 and rtf support
Handle case where very small files causes an exception to be thrown on validation

Related Issue

#122

Motivation and Context

Expanded support for file validation

How Has This Been Tested?

This was tested on a dev laptop
obelisk was built locally
a working project was updated to use the local version of Obelisk as a project dependency
The code was stepped through and tested

Types of changes

• 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.
• 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.