Install all dependencies
Don't _build_ vignettes
Also declare cran mirror for install_github
Minor Debian/Ubuntu tweak

One just needs r-base-dev, it pulls in r-base-core.  And one doesn't need the doc packages pulled in by the (meta-)package r-base.
Merge pull request #2 from hadley/patch-1

Install all dependencies
Merge pull request #8 from eddelbuettel/patch-1

Minor Debian/Ubuntu tweak
Use stricter (cran) checking
One more thing to do...
Merge pull request #13 from krlmlr/patch-1

One more thing to do...
Merge pull request #11 from hadley/patch-2

Use stricter (cran) checking
Update README.
Merge branch 'master' of https://github.com/eddelbuettel/r-travis into
merge-dirk

Merged Dirk's changes roughly verbatim, still need to test.

Conflicts:
	scripts/travis-tool.sh
Do a little tidying/normalization.

This does two things:
 * sets indentation to 4 (egads!)
 * makes devtools use uniform, with a note that it might be made optional.
Tweak Dirk's changes to get things passing again.
Add .Rbuildignore.

closes #22
Add notification info, restrict branch for build shield.
Add an apt package to our test package (for testing).

closes #14
do not hard-code the Ubuntu release name

can use `lsb_release -cs` instead
Installing R from a CRAN binary package instead of homebrew
Triggering a build with an edit of README