BEL validation/pipeline performance

[wshayes]

We can do a batch request to arangodb for multiple terms/orthologies to speed things up.

We can also do the same for Elasticsearch queries: https://www.elastic.co/guide/en/elasticsearch/reference/current/search-multi-search.html

Look into using asyncio for processing many nanopubs/assertions at a time. Use asyncio semaphore to not overload the system by limiting the number of nanopubs/assertions to run at the same time.