report running versions of packages on api

(webapp, soledad, mx)

if the api can expose these strings, we can make the client refuse to run with an obsolete provider. this would also be needed for the client to be able to run data migrations when we decide that we should care about our user base data stability.

for the python packages, use package.version, see https://github.com/kalikaneko/dotfiles/blob/master/scripts/pyver

(from redmine: created on 2013-11-07, closed on 2014-01-08)