expand design, enough detail to start implementation
External special remote protocol now includes commands for setting and getting the urls associated with a key.
add stub claimUrl
implement CLAIMURL for external special remote
Urls can now be claimed by remotes. This will allow creating, for example, a external special remote that handles magnet: and *.torrent urls.
Merge branch 'master' of ssh://git-annex.branchable.com