wowVersions not strictly necessary

[t-mart]

Though the schema requires it now, functionally, we don't need a wowVersions attribute in the configuration to run wap. It only is required to:

• Generate TOC files
• Link to Interface/Addons
• Publish

These tasks are pretty juicy value props to wap, but you don't have to do em. So, strictly, wowVersions isn't necessary and we should update the schema and make it an optional value in code.

Or, maybe decide that we should keep it.