BibRank: improvements to citerank sources and docs

• Plug citerank methods into the demo site

• Write about citerank into BibRank Admin Guide

• Write about citerank into BibRank Hacking Guite

• Move the MARC tags for the publication dates into the cfg files

• Fix the weighting of citerank, so it is more user friendly (normalize it at 100)

• Some optimizations to the citerank code