virtualenv conditional

[thefinn93]

Installation of the virtualenv package doesn't work on older OSs (older than Debian jessie or Ubuntu Vivid), but on newer OSs need it over python-virtualenv (see #6). We should improve the conditional to reflect this nuance.

[pmackay]

I'd like to get this role working on Ubuntu 14.04. Would pmackay@e47e389 be ok to do a PR? Not sure if this generalizes the solution enough though.

[thefinn93]

eh i guess. Not ideal but whatever. Maybe someone will come along and fix it all one day...

[pmackay]

Do you happen to know of any matrix that lists all the distributions and versions? And a simple way to determine the right package for each? Or is it a case of trial and error testing or looking up for each one?

[pmackay]

I've done a more generalized approach here pmackay@f0d33e7. Does that seem OK?

Have also created a travis-test branch that sets up testing the role on Travis, which I could also raise a PR for if that sounds useful?

[thefinn93]

PR the travis branch for sure! I'm wrapping of my last quarter of university so I'm gonna be focusing on finals for a bit, I'll take a look at the other thing sometime next week

[pmackay]

Have created #34, feedback welcome whenever is convenient.