* skip auth

* update docs and extend to versioned images

This was forgotten in the previous commit, where only the non-devel images
where tested.

All the rocker r-base/r-apt based images already have the R recommended
packages pre-installed, see e.g. [0].

By installing the recommended packages also on the r-ver based images the
compatibility with packrat is improved, when it is used in a mixed mode
on top of different distribution with recommended packages pre-installed
and r-ver based images. Packrat does not include recommended packages in
its package library packrat.lock, if those are in the system library,
see also the pakrat docu page 5 in [1]. This leads to unresolved
dependencies and would require manually adding those also to the packrat
library.

The R installer already includes a mechanism to also install the
recommended packages, which is just activated by this change. The R
recommended packages are also versioned by the R version, see [2]-[6].

[0] r-recommended: https://github.com/rocker-org/rocker/blob/master/r-base/Dockerfile#L50
[1] https://cran.r-project.org/web/packages/packrat/packrat.pdf
[2] https://cran.r-project.org/src/contrib/${R-Version}/Recommended/
[3] https://cran.r-project.org/src/contrib/3.5.1/Recommended/
[4] R_PKGS_RECOMMENDED: https://github.com/wch/r-source/blob/trunk/share/make/vars.mk
[5] https://github.com/wch/r-source/blob/trunk/src/library/Recommended/Makefile.in
[6] https://github.com/wch/r-source/blob/trunk/tools/rsync-recommended

fixes https://github.com/rocker-org/rocker/issues/299, thanks @dmenne 

ggplot2 3.0 suggests sf, we do not want tidyverse to become rocker/geospatial quite yet

no longer is this installed by some above dependency. this is needed by
gnu tar to untar the tlmgr setup

* Add RStudio default settings for handling history (#79)

Added to Dockerfiles:

- mkdir /home/rstudio/.rstudio/monitored/user-settings

- create file /home/rstudio/.rstudio/monitored/user-settings/user-settings

	- alwaysSaveHistory = FALSE
	- loadRDate         = FALSE
	- saveAction        = FALSE

- chown rstudio /home/rstudio/.rstudio (Must be done else RStudio will not
  load; generates error message).

Originally, this was added to all Dockerfiles in subdir rstudio. However, on
tidyverse builds these settings were overwritten somehow (user-settings file
existed but contents were slim and not equal).

Added similar section to all tidyverse Dockerfiles.

Sample test builds of rstudio and tidyverse images verify settings work as
expected.

* Add RStudio user-settings file

* Modify commit @00bd6da, COPY user-settings to img

Undo changes to RStudio Dockerfiles in commit 00bd6da.

COPY user-settings (commit de308a4) to image on build.

Change ownership of ~/.rstudio directory to rstudio to prevent "Error occured
during the transmission" errors that will prevent RStudio from loading.

See: #79, #80

* Undo tidyverse changes in commit 00bd6da