Beta API changes

Clean up some inconsistencies in the API:

Alpha               Beta
(None)              Get-AudioLibrary
New-AudioLibrary    New-AudioLibrary

Update-AudioFile    Update-AudioLibrary
Backup-AudioFile    Backup-AudioLibrary

Get-AudioFile       Get-AudioFile
Add-AudioFile       Add-AudioFile

With this set of commands, access to database updates occur on the Noun AudioLibrary and access to invididual file entries occur on the Noun AudioFile.