add Caesar

[fibo]

Caesar is a desktop app based on Electron.

For now it supports Mac and Windows.

It is at an early stage, I just released a first basic version that lets encrypt/decrypt files using a passphrase.

It can generate a passphrase with up to 10 BIP39 words.

By design it never connects to the Internet, automatic updates are not implemented.

It has no dependencies other than typeage.