Fix missing node bindings in NodeNorm /query output

[gaurav]

As reported in #229. As far as I can tell, this was caused by merged_binding being None, which could cause it to end up being an object later in the code. Handling the case where it's None appears to fix this problem as per the simple test in PR TranslatorSRI/babel-validation#26.

Fixes #229.

[cbizon]

Is that localhost entry in the openapi going to make it into the version hosted at the smartapi registry?

[gaurav]

NameRes uses the same servers setup, so we can use that see what happens.

Bad news: the localhost entries do get picked up by SmartAPI via Yaphet's trapi-openapi app: https://trapi-openapi.apps.renci.org/utility/infores%3Asri-name-resolver?version=%2A

Good news: those localhost entries somehow gets magically turned into the current server name on https://name-resolution-sri-dev.apps.renci.org/docs, https://name-resolution-sri.renci.org/docs and https://name-lookup.ci.transltr.io/docs and in the trapi-openapi app. So the server does gets duplicated, but localhost:2433 never itself gets added. So it should work the same for NodeNorm.

I'm going to ask @YaphetKG to review this PR as well in case there's a better way to do what I'm trying to do here.

[gaurav]

I should have added in my previous comment that I've deployed this to https://nodenormalization-dev.apps.renci.org/docs and that does correctly transform localhost to the URL (i.e. https://nodenormalization-dev.apps.renci.org/1.4). So that localhost entry should be fine.