[Brightbox] Rename old destroy requests to delete

To standardised with the Delete in CRUD we decided to update the API
documentation but had used the old names in the Fog requests.

This replaces them with deprecation to the old methods so they continue
to work as before.
[Brightbox] Documentation fixes

Fixes yardoc for request methods.
Merge pull request #1818 from fog/brightbox_updates

[Brightbox] Updates to delete requests and doc fixes