Reformat with black (dj-stripe#928)

Also

* changed isort config to match black (see https://black.readthedocs.io/en/stable/the_black_code_style.html?highlight=.isort.cfg#how-black-wraps-lines )
* changed editorconfig + isort to space instead of tabs
* updated most other files to replace tab with 4 space.
* set flake8 limit to 88 to match black default

Resolves dj-stripe#926

.editorconfig

@@ -5,7 +5,11 @@ root = true
 charset = utf-8
 end_of_line = lf
 indent_size = 4
-indent_style = tab
+indent_style = space
 quote_type = double
 insert_final_newline = true
 trim_trailing_whitespace = true
+max_line_length = 88
+
+[*.json]
+insert_final_newline = false

HISTORY.rst

@@ -36,12 +36,12 @@ Changes from API 2019-02-19:
 
 - Special handling of the icon and logo fields:
 
-	- Renamed ``Account.business_logo`` to ``Account.branding_icon``
-	  (note that in Stripe's API ``Account.business_logo`` was renamed to ``Account.settings.branding_icon``,
-	  and ``Account.business_logo_large`` (which we didn't have a field for) was renamed to ``Account.settings.branding_logo``)
-	- Added deprecated property for ``Account.business_logo``
-	- Added ``Account.branding_logo`` as a ForeignKey
-	- Populate ``Account.branding_icon`` and ``.branding_logo`` from the new ``Account.settings.branding.icon`` and ``.logo``
+    - Renamed ``Account.business_logo`` to ``Account.branding_icon``
+      (note that in Stripe's API ``Account.business_logo`` was renamed to ``Account.settings.branding_icon``,
+      and ``Account.business_logo_large`` (which we didn't have a field for) was renamed to ``Account.settings.branding_logo``)
+    - Added deprecated property for ``Account.business_logo``
+    - Added ``Account.branding_logo`` as a ForeignKey
+    - Populate ``Account.branding_icon`` and ``.branding_logo`` from the new ``Account.settings.branding.icon`` and ``.logo``
 
 Changes from API 2019-03-14:
 
@@ -566,9 +566,9 @@ BIG HUGE NOTE - DON'T OVERLOOK THIS
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 .. warning::
-	Subscription and InvoiceItem migration is not possible because old records don't have Stripe IDs (so we can't sync them). Our approach is to delete all local subscription and invoiceitem objects and re-sync them from Stripe.
+    Subscription and InvoiceItem migration is not possible because old records don't have Stripe IDs (so we can't sync them). Our approach is to delete all local subscription and invoiceitem objects and re-sync them from Stripe.
 
-	We 100% recommend you create a backup of your database before performing this upgrade.
+    We 100% recommend you create a backup of your database before performing this upgrade.
 
 
 Other changes

djstripe/__init__.py

@@ -10,19 +10,24 @@
 
 
 class DjstripeAppConfig(AppConfig):
-	"""
-	An AppConfig for dj-stripe which loads system checks
-	and event handlers once Django is ready.
-	"""
+    """
+    An AppConfig for dj-stripe which loads system checks
+    and event handlers once Django is ready.
+    """
 
-	name = "djstripe"
+    name = "djstripe"
 
-	def ready(self):
-		import stripe
-		from . import checks, event_handlers  # noqa: Register the checks and event handlers
+    def ready(self):
+        import stripe
+        from . import (  # noqa: Register the checks and event handlers
+            checks,
+            event_handlers,
+        )
 
-		# Set app info
-		# https://stripe.com/docs/building-plugins#setappinfo
-		stripe.set_app_info(
-			"dj-stripe", version=__version__, url="https://github.com/dj-stripe/dj-stripe"
-		)
+        # Set app info
+        # https://stripe.com/docs/building-plugins#setappinfo
+        stripe.set_app_info(
+            "dj-stripe",
+            version=__version__,
+            url="https://github.com/dj-stripe/dj-stripe",
+        )