R Travis-CI conf for rstan rstantools

.travis.yml

# CL personal adjustment form https://discourse.mc-stan.org/t/rstan-rstantools-travis/6102

language: R
sudo: true
cache: packages

env:
 - MATRIX_EVAL="CC=gcc-7 && CXX=g++-7"

r_packages:
 - backports
 - remotes
 - devtools
 - tidyselect

apt_packages:
 - libgsl0-dev
 - libxml2-dev
 - openjdk-7-*

addons:
 apt:
  sources: ubuntu-toolchain-r-test
  packages: g++-7

r:
 - release
 - oldrel

os:
 - linux
 - osx

matrix:
 exclude:
  - r: devel
    os: osx

after_success:
 - Rscript -e 'covr::codecov()'