Initial Travis setup

[rgbkrk]

This uses https://github.com/craigcitro/r-travis to setup Travis builds for rzmq. You'll need to add the actual integration with Travis after merge.

[armstrtw]

could you walk me through this? perhaps via email? or just send a link to your favorite documentation for travis? thx.

[rgbkrk]

Actually, it looks like Travis now supports R directly. I'll have to update this PR now.

[armstrtw]

Right. We have this working for Rblpapi, so I can just copy the config over changing the account... I assume there is some account that needs to exist over at the Travis site.

[rgbkrk]

Travis is tied to the owner of the repo. Since yours is under a user, it's under your control to enable within

https://travis-ci.org/profile/armstrtw

Here's the starter guide that Travis offers, though you'll probably be able to flip a switch on your profile that looks like this:

to this:

[rgbkrk]

I'm clearing out all my old PRs. Feel free to revisit if someone wants it.