RESTful API for the future shatag server:

$URL is the service endpoint, https://example.com/shatag

send a bunch of hashes:

POST $URL/host/<hostname>
Data: json document containing [{'clear': root},{'path':path, 'hash':hash},...]

check if a hash exists:

GET $URL/where/<hash>
Data: document containing { hash: [host, host, ...] }

GET $URL/find/<hash>
Data: document containing { hash: { host: [path], host: [path], ...}}
