Fix integration tests

[sambrightman]

• Always check return value of ntfy_main (no longer using exceptions)
• Do not use a dict as the default of args.option

The latter accidentally shared state across tests, breaking all
integration tests. However, this was hidden because exceptions are now
caught and integration tests were not checking return values.

[sambrightman]

It's not clear to me where the ntfy[xmpp] dependency should go to run the integration test for an optional feature. This failure was previously being hidden as mentioned. CI should pass if .[xmpp] is added to the install lists, but don't think it can go into tests_require? ntfy[xmpp] there would refer to the previously released version. Maybe just get CI passing?

[coveralls]

Coverage increased (+7.01%) to 85.115% when pulling b5c8601 on sambrightman:integration_tests into 91c84c3 on dschep:master.

[coveralls]

Coverage increased (+7.01%) to 85.115% when pulling d41f997 on sambrightman:integration_tests into 91c84c3 on dschep:master.

[sambrightman]

Pushed the changes to get CI working, not sure if most appropriate.

[coveralls]

Coverage increased (+7.01%) to 85.115% when pulling 62b3537 on sambrightman:integration_tests into 91c84c3 on dschep:master.

[coveralls]

Coverage increased (+7.01%) to 85.115% when pulling 62b3537 on sambrightman:integration_tests into 91c84c3 on dschep:master.

[dschep]

Awesome. thanks! That way of handling the xmpp req is fine :)