sheesy-cli 2.0.0

The 'share-secrets-safely' CLI to interact with GPG/pass-like vaults.
## V2.0.0: Better user onboarding experience

### Improvements

 * `vault list` now produces precise URLs.
 * `vault remove` can remove resources from the vault.
 * `vault recipient add` now signs and re-exports added fingerprints to make
   recipient verification part of adding them, and help build a *Web of Trust*.
 * `vault recipients remove` removes recipients and re-encrypts the vaults content.
 * `vault recipient add` also adds recipients which are only in your gpg keychain.
    Previously it would always require an exported public key in the right spot.
 * `vault recipient add --verified` allows to add any recipient by name, but requires
    you to assure you are able to encrypt for that recipient.
 * `vault add` now creates sub-directories automatically.
 * `vault edit` now tries to encrypt before launching the editor.
 * `vault add :something` with a tty as standard input will open an editor automatically.

### Breaking Changes

The breaking change requiring a major version increment is changes to the `sy-vault.yml` file.

 * The `at` field is now called `secrets`
 * `recipients` and `gpg-keys` paths are no relative to the `sy-vault.yml` file, not relative to the
   `secrets` directory.
 * The '--at/-a' flag of `sy vault` is now `--secrets-dir-dir/-s`
 * `recipients add` will now require fingerprints unless `--verified` is specified.

These improvements make handling paths consistent and less suprising.

## V1.0.1: The very first release - with a new name!

`s3` now officially is `sy` on the command-line, and spelled `sheesy`. Crates
were renamed accordingly, too.

## V1.0.0: The very first release!

This is the first usable version, providing only the minimal amount of features.
A lot of the value contained is a fully automated system for quality assurance
and deployment, which will help keeping the releases coming.

 * [x] **setup rust workspace for clear dependency separation**
 * [x] **setup CI for linux and OSX**
 * [x] **standalone deployables without additional dependencies for**
   * [x] OSX (static binary) - _just gettext is still dynamically linked :(_
   * [x] MUSL Linux
 * [x] **shell completions**
 * [x] **complete a happy journey with**
   * [x] initialize a new vault
   * [x] add contents
   * [x] support for multiple vaults
   * [x] list vault contents
   * [x] decrypt vault contents
   * [x] edit vault contents
   * [x] add another user and re-encrypt vault content
 * [x] **installable from crates.io**
 * [x] **release binaries generated by travis for tags**