correction for empty config vars
added rserve example
updated download path for glibc
glibc archive no longer contains nested archive
Update pixman version to agree with LATEST on cairographics.org
Update Cairo version
Don't use LATEST for pixman and Cairo.  Too fragile.
Merge pull request #22 from btubbs/master

Update pixman and Cairo versions
added additional message in vagrant install script
added support for building binaries without vulcan
added support for overriding recommended packages
quote variables
added outputs
added comment about logging
may need R_HOME and R_INCLUDE environment variables when building packages
need vars.mk
more outputs
can't sync recommended packages ~ rsync not installed on cedar
correction for propagation of r version variable
show arguments