Belvo-python

Changed:
* [BEL-75] Allow resume operation on Incomes resource (91)

Other:
* Change link for link_id in data (92)
* Bump version 0.20.0 (93)

Changed:
* Update dependencies (80)
* Reorganize resources (81)
* Stop sending AccessMode.SINGLE by default when creating a Link (82)
* Allow WidgetToken to create link-scoped tokens (83)
* Reorganize resources tests (84)

Fixed:
* Balance date_to as obligatory param (75)
* Rollback date_to as optional (76)

Other:
* Bump version: 0.17.1 → 0.18.0 (85)

Project setup working again

* We have had the installation of the package broken for some days. They where changes on the way of deployment that where preventing the project to successfully be used once installed.

* We have fixed the setup process and now we can install and import the `belvo` namespace without issues.

Fixed
- Added `name` and `url` to project `setup.py`

Added
- `WidgetToken` resource to allow creating tokens for the Belvo Widget from our python library.

Example:
python
from belvo.client import Client

my_client = Client("my-secret-key-id", "my-secret-key-password", "https://sandbox.belvo.co")
token = my_client.WidgetToken.create()

print(token["access"])

Added
- Add `certificate` and `private_key` to link create/update
- Add `username_type` to update link