use_travis() should have CRAN and bioc args

<a href="https://github.com/hadley"><img src="https://avatars0.githubusercontent.com/u/4196?v=3" align="left" width="96" height="96" hspace="10"></img></a> **Issue by [hadley](https://github.com/hadley)**
_Thursday Jun 23, 2016 at 18:24 GMT_
_Originally opened as https://github.com/hadley/devtools/issues/1236_

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- CRAN would add 3 r versions
- bioc would add 2 bioc versions

