Remove lock from documents that fail to close

[nezuo]

Example implementation:

UpdateAsync(function(oldData)
    if oldData.lockId == document.lockId then
        oldData.lockId = nil
        return oldData
    end

    return nil
end)

As long as the current lock is still the same as the documents, it should be safe to remove it.

[nezuo]

These are the cases a document will fail to close that we should attempt to remove the session lock:

• validate throws an error.
• data fails to pass validate
• beforeSave errors
• beforeClose errors

[nezuo]

Closed by #66.