Use coveralls for astropy?

`scipy` recently started using https://coveralls.io, i.e. coverage reports are generated by travis-ci and posted here: https://coveralls.io/r/scipy/scipy

I find this to be a useful record to have, both for new bug reports and for for new code in pull requests, one can quickly check coverage and ask for more unit tests if important lines are completely un-tested.

It's free and easy to turn on ... do we want to use coveralls for `astropy`?

Alternatively, someone please check why the coverage report at
https://jenkins.shiningpanda.com/astropy/job/astropy-coverage/
hasn't been updated for 16 days. (@astrofrog, do you maintain it?)