Fix setting of default affiliation (or falling back on 'member') on node...

... subscriptions

Fixes #121

Currently it looks like all new subscriptions are getting an affiliation of 'none' regardless of the default affiliation configuration, this isn't good.

Added tests for this. Should the configuration value not exist then there is a fallback to 'member' now.

Once this gets merged I'd suggest deploying the latest version with this included.

@imaginator @abmargb