Django-polaris

Introduces support for anchoring multiple assets and includes a redesign of the UI.


**Note:** This release introduces a *breaking change* by changing the `form_for_transaction()` return type. It also adds several packages and setup commands needed to run Polaris. The [docs](https://django-polaris.readthedocs.io/en/v0.9.14) have been updated to reflect this.

A bug that saved completed transactions with a status of pending_anchor after successfully submitting a transaction to the network has been fixed. This bug was introduced in 0.9.3. This release also includes other minor bug fixes and improvements.

Anchors can now opt out of using the Form Integration system for the interactive flow in favor of an another application external to Polaris. Also includes bug fixes and refactoring.

Polaris now provides an interface for specifying your stellar.toml fields as per [SEP-1](https://github.com/stellar/stellar-protocol/blob/master/ecosystem/sep-0001.md).

Adds short-lived JWT authentication to the `/deposit` and `/withdraw` interactive flows. Also adds an integration point for providing deposit instructions for users after initiating a deposit request through their wallet.

Other changes:
- Renamed `to_address` and `from_address` JSON response fields to `to` and `from`
- Created `PolarisSameSiteMiddleware` to be installed in your `settings.MIDDLEWARE`
- Removed the unnecessary `/confirm_transaction` endpoint