Remove duplicate listing of collaborators + Add consistent space after CP/SP index: for better appearance

[yarikoptic]

Duplication (especially avoidable) is not good. While looking at the list of the projects I realized that we have two places:

• on https://www.repronim.org/community.html
• on https://www.repronim.org/collaborators.html

I think it is good to have in a single place and thus left only community one, but added an id so we could point to it directly.

TODOs

• [x] may be add redirector for former collaborators.html if someone linked it from outside
• [x] verified that redirect works locally
• [ ] verify (@juliebates ?) that it was identical listing indeed