T2 improve matching w/o postcode: reduce computational time and number of potential matches

[Tilmon]

Dear @maurolepore ,

this is a reminder ticket to think a bit about how to improve the matching process for loanbook companies without postcode in the future. This is, however, not relevant for v1. Therefore, I put it down for a sprint at the end of March.

[maurolepore]

Thanks @Tilmon

I tagged with the milestone v2 which you can edit and describe here.