Revert "Replace rake functions with python paver functions"

This reverts commit df2e410f2a8ca8ceeebfc7dc665a9f731ea3884c.

Tests are failing in master.  For some reason, the new paver commands think that node prereqs are installed when they are not.  I'm not sure why this is happening, but I suspect something funky is going on with paths in the multi-config job in Jenkins.

Until I can get to the bottom of this, I'd like to back out the paver commit.  Very sad :(

@jzoldak