Add a flag to turn off higher rank fallback for common name lookup and add the rank of the common names

[thompsonmj]

Based on the discussion in #14 and among team members in Slack, reporting the rank of the common name that was retrieved, especially when it does not match the rank of the most granular Latin term, is needed.

Furthermore, an option to not fall back to higher ranks for common name 'umbrellas' should be added such that when no common name for the most specific available Latin term exists, it is simply left null.