fix ubuntu-rstudio and ubuntu-hadleyverse (missing packages), and missing \ in debian-hadleyverse
Merge branch 'sandbox' of github.com:eddelbuettel/rocker into sandbox
clean /tmp/downloaded_packages/
changes to r-base

- install 'ed' (which, believe it or not, nloptr needs in configure and BDR did not let me use sed ...)
- reorder installation of .deb binaries in sorted order
- update before install in same RUN
- append to, rather than overwrite, Rprofile.site
remove duplicate install (from debugging)
Merge branch 'sandbox' of github.com:eddelbuettel/rocker into sandbox
added links for ubuntu-{rstudio,hadleyverse} to README
Merge branch 'sandbox' of github.com:eddelbuettel/rocker into sandbox
updated / standardize Dockerfile(s) for r-devel
add new r-devel-san build for debian
Merge pull request #21 from eddelbuettel/sandbox

merge current Sandbox state to trigger updated builds