Removed directory from clean task.

.tmp/css is no longer used so can be removed from clean task.
Removed caching from download task.

It seems that HEAD request was making some downloads slow. WSDLs are
quick to download so I don't think the cahcing is required anyway.
Embed version number into pages.
Remove 'Last Update' from pages.
Update list of services to match offical documents.

Offical documents can be found at

https://go.developer.ebay.com/developers/ebay/documentation-tools/

Note I only include those that have an available WSDL.