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
Users can choose whether to have these features on or off now. And
a platform admin can still use the same controls to switch the features
on or off on behalf of a user. There’s no need for the separate buttons.
As before the service manager will not be able to change the Text message sender once they have the inbound sms permission.
If the inbound sms permission is turned off the Text message sender setting is once more configurable by the service manager.
The inbound number remains bound to the service, but has "inactive", so that the number can not be used again.
