Clean up scripts/

Check for an internationalised filename first

Support unicode attachment filenames

Don't loop over all rooms ever in typing.get_new_events_for_user

Add config option to specify where generated files should be dumped

Allow specifying directories as config paths

Allow specifying a directory to host a web client from

Add utility to parse config and print out a key

Usage:

```
$ python -m synapse.config read server_name -c homeserver.yaml
localhost
```

Revert previous commit. Instead, always download matrix-angular-sdk as a requirement, but don't complain (when we do check_requirements) if we don't have it when we start synapse.