Missing is_allele_of associations in ZFIN ingest

[kshefchek]

I've been working on our gene-variant display and am auditing our data. In doing this I found that we're missing two allele-gene relationships for shha. According to the ZFIN and AGR sites shha has 6 alleles, we're missing:

https://zfin.org/ZDB-ALT-010427-6
https://zfin.org/ZDB-ALT-010427-8

In both cases we're linking the gene to a blank node connected to these, but I think we should have the edge connected to both, or just to the non-blank node version. The behavior is inconsistent here since we're getting the other four.