Uniprot sourcename fix

[bsantan]

• Fix in merge.yaml to look in uniprot_genome_features for transformed files
• Fix in uniprot.py to us Uniprot prefix in protein IDs rather than uniprot_genome_features prefix

[hrshdhgd]

Instead of hardcoding strings I'd recommend using constants.py to declare as a variable first and then use it in the project

[bsantan]

I added constants to the uniprot.py file rather than strings.

[hrshdhgd]

Looks good! Let's push to merge #107 first and then we can merge this one. I have a suspicion there will be conflicts with this branch that'll need manual intervention. But we'll deal with it when we get there. Undo the changes you made in tox.ini. #107 seems to have been fixed. So once we merge down the main branch to this one, all should be fine!