Signature is not possible to construct in JS out of the box

[octatone]

Looking at the docs for pseudo-client implementation I see some issues for the web for generating the signature header:

• sha256 - no api for this in browser land - would have to implement in JS
• mdb5hex - no api for this in browser land, although we do have a basic implementation as part of the webapp - not sure that is to spec
• shared secret - there's no way to hide this in the client from anyone who wants to find it, is that okay?

https://github.com/wunderlist/hamustro/blob/master/docs/pseudo-client.md#send-events-to-the-collector