roll-back pyina to depend on pp-1.6.4.1 explicitly
added which.py to check pyina install; fix optimize_rosen_powell_map typo


git-svn-id: svn+ssh://svn.mystic.cacr.caltech.edu/pathos/pyina@681 8bfda07e-5b16-0410-ab1d-fd04ec2748df
Merge branch 'master' of https://github.com/uqfoundation/pyina