fix(Biorxiv search query)Added query string for space separated params

The merge request addresses the issue: #862 (closed)

Changes include:

1. Created a query string as per the issue description instead of handling space-separated elements by exploding into different params
2. Modified the biorxiv query handling a bit.

Note by Ben: I originally exploded this into multiple queries because I couldn't figure out how to get multi-word phrases to play nicely in this conjunction (OR) query. Putting double quotes around each phrase solves this, so we can scrap the logic that generated multiple queries and combined their results together. PK started on this work and I have finished it off.