multiple stores

[annihat]

please allow multiple stores possibly using tags as in #56.

#56 suggests using a comma separated list but currently whatever you put in there is a single item, for instance "Lidl, Aldi, Tesco" is not the same as "Aldi, Lidl, Tesco", in my request (& in #56) these would be 3 separate stores (although possibly sorted into a per-item preference order)