Added linter, fixed some lint errors
Prettified CSS and Javascript, rearrange handlers.
style improvements
Incoming mail: don't panic on wrong address

Instead, if we have no user for a given To address, we simply
don't encrypt that mail.

For now, store it for easier debugging.

Eventually, we will probably change it to drop such mail.

(The SMTP server already notifies senders if the recipient
address is not found.)
Docs: fixed scroll bug, decoupled doc CSS from app CSS
Deployment: added Postfix config for email updates
Don't Panic!
cache notaries to sessionStorage
UI: Cache public key lookups for speed
Updated slideshow
Style changes for hashed.im