Remove duplicates from taxonomic spine

[FedorSteeman]

Issue

Once the auto-merging as per #74 has been done, we need a process for remove these duplicates also from taxonomic spine stored in local app database.

Remarks

Removing duplicates in a taxonomy is non-trivial as duplicates can be hard to identify due to slight spelling variations.
In a database system such as Postgres you have the option of finding close matches by using Levenschtein distance or other string metrics for identifying duplicate candidates.

[FedorSteeman]

Prerequisite is a smarter way to handle database as per #185

[FedorSteeman]

Solved in conjunction with #185