joken breaking changes

• v2.3.0 \u2192 v2.4.0breaking

  Change of CI pipeline (thanks to @dolfinus)

• v2.3.0 \u2192 v2.4.0breaking

  Now uses Elixir 1.8 as minimum (and actually test the mininum version on CI)

• v0.15.0 \u2192 v0.16.0breaking

  The new API is completely different than the old one. Take a look [here to find out how to go from 0.15 to 0.16](https://github.com/bryanjos/joken/wiki/Moving-from-0.15-to-0.16)

• v0.15.0 \u2192 v0.16.0breaking

  `encode` and `decode` in the Joken module have been renamed to `sign` and `verify`.

• v0.15.0 \u2192 v0.16.0breaking

  This release also deprecates [plugJWT](https://hex.pm/packages/plug_jwt). Use `Joken.Plug` instead

• v0.13.1 \u2192 v0.14.0breaking

  `Joken.Codec` is replaced by `Joken.Config`.

• v0.13.1 \u2192 v0.14.0breaking

  `json_module` in config is replaced by `config_module`.

• v0.13.1 \u2192 v0.14.0breaking

  `algorithm` and `secret_key` in config is replaced by implementing the `algorithm` and `secret_key` functions on `Joken.Config`.

• v0.13.1 \u2192 v0.14.0breaking

  `Joken.Token.encode` now has a signature of `(joken_config, payload)` since the algorithm and secret key are defined inside of the passed in `joken_config` module.

• v0.13.1 \u2192 v0.14.0breaking

  `Joken.Token.decode` now has a signature of `(joken_config, jwt, options \\ [])` since the algorithm and secret key are defined inside of the passed in `joken_config` module.

Get this data programmatically \u2014 free, no authentication.