Ignore scaffolds/ when running tests
Allow scan locations to be specified in settings

Added `tangled.app.scan` setting.
Allow resources to be specified via settings

Added `tangled.app.resources` setting, which should be lists of args
for `Application.mount_resource()` on separate lines.

[app]
tangled.app.resources =
    home, mypackage.resources:Home, /
    user, mypackage.resources:Users, /users/<id>
Allow static directories to be specified via settings

Added `tangled.app.static_directories` setting, which should be lists of
args for `Application.mount_static_directory` on separate lines:

[app]
tangled.app.static_directories =
    docs, /var/www/example.com/docs
Allow the event_type and func args to add_subscriber to be strings
Add @subscriber decorator
Correct comment