[pymvpa] Handling of references

[Yaroslav Halchenko]

> P.S. I hope nobody would mind much if I add Emanuele's referenced paper
> into our papers bib/pdf (along with bibtex entry) -- it seems to be a
> nice overview, worth referring to
oops -- I managed to commit it to neuroim branch... sorry...
cherry-picked also into master
-- 
Yaroslav Halchenko
Research Assistant, Psychology Department, Rutgers-Newark
Student  Ph.D. @ CS Dept. NJIT
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