Merge pull request #111 from eddelbuettel/master

adding a curl-and-dpkg method
Add a PPA for TeX packages.

Fixes #113.
Don't build vignettes.
Since we don't ever look at them
Install_deps is now exported
Merge pull request #114 from hadley/devtools_tweaks

Devtools tweaks
Update travis build shield to svg from png.

[ci skip]
Add to README.

[ci skip]
Update travis-tool.sh
Update travis-tool.sh
Update travis-tool.sh
Update travis-tool.sh
Update travis-tool.sh
Update travis-tool.sh
Merge pull request #118 from thirdwing/master

Install an R dependency from Bioconductor
Tweak a few names in the bioc commands.

Also adds a test.
Update a test.