Fix default value of photos year.
Fix default value of photos year.

Seems like api does not always have photos era OR year, for example https://hkm.finna.fi/Record/hkm.HKMS000005:0000000f
So default to empty string if era is not available.

andersinno/kuvaselaamo,andersinno/kuvaselaamo,andersinno/kuvaselaamo