Add concept scheme as qualifier to terms alphabetical index

[osma]

At which URL did you encounter the problem?

http://dev.finto.fi/iptc/fi/index?clang=en

What steps will reproduce the problem?

1. Go to IPTC
2. Look at alphabetical index in English

What is the expected output? What do you see instead?

It is not clear that some terms are from Scene whereas others are from Subject Code. We could automatically add a qualifier to the terms indicating their concept scheme.

[tfrancart]

+1 to this with respect to situations with multiple concept schemes described in #634