Tweak how R packages are built.

Add bzip2 as a dependency to base R.

Switch from installing the R packages from tar files to installing from
the extracted directory. This is more in line with a standard install
and also allows installing from VCS.

Use the Bioconductor version for BiocGenerics and future Bioconductor
packages. Suffix the package with 'bioc-$version' to indicate which
Bioconductor release the package is a part of. This is actually more
important than the actual version attached to individual packages
although those are subject to change within the Bioconductor branch.

var/spack/repos/builtin/packages/r-abind/package.py

@@ -34,11 +34,11 @@ class RAbind(Package):
     homepage = "https://cran.r-project.org/"
     url = "https://cran.r-project.org/src/contrib/abind_1.4-3.tar.gz"
 
-    version('1.4-3', '10fcf80c677b991bf263d38be35a1fc5', expand=False)
+    version('1.4-3', '10fcf80c677b991bf263d38be35a1fc5')
 
     extends('R')
 
     def install(self, spec, prefix):
 
         R('CMD', 'INSTALL', '--library=%s' %
-          self.module.r_lib_dir, '%s' % self.stage.archive_file)
+          self.module.r_lib_dir, '%s' % self.stage.source_path)