Enforce order and style of imports

Done using isort[1], with the following command:
```
isort -rc ./app ./tests
```

Adds linting to the `run_tests.sh` script to stop badly-sorted imports
getting re-introduced.

Chosen style is ‘Vertical Hanging Indent’ with trailing commas, because
I think it gives the cleanest diffs, eg:
```
from third_party import (
    lib1,
    lib2,
    lib3,
    lib4,
)
```

1. https://pypi.python.org/pypi/isort

app/main/views/user_profile.py

@@ -2,30 +2,27 @@ import json
 
 from flask import (
     abort,
-    render_template,
+    current_app,
     redirect,
-    url_for,
+    render_template,
     session,
-    current_app)
-
-from flask_login import login_required, current_user
+    url_for,
+)
+from flask_login import current_user, login_required
 from notifications_utils.url_safe_token import check_token
 
+from app import user_api_client
 from app.main import main
-
 from app.main.forms import (
-    ChangePasswordForm,
-    ChangeNameForm,
     ChangeEmailForm,
     ChangeMobileNumberForm,
+    ChangeNameForm,
+    ChangePasswordForm,
     ConfirmMobileNumberForm,
-    ConfirmPasswordForm
+    ConfirmPasswordForm,
 )
-
 from app.utils import is_gov_user
 
-from app import user_api_client
-
 NEW_EMAIL = 'new-email'
 NEW_MOBILE = 'new-mob'
 NEW_MOBILE_PASSWORD_CONFIRMED = 'new-mob-password-confirmed'