ENH: run nipy and dipy in both wheezy and sid chroots for sparc + RF

NB There are uncommitted changes on the buildbot master box, so decided to go with the PR instead of direct push/pull/reconfig

RF: unified referencing of python on those releases where it is
already known for sure (thus 2.7-wheezy instead of non-informative
2.x-wheezy)

also added printout of versions for pandas (hope it works)