Make R extensable and add a couple of packages for verification.

Added R as a build system so that the create template will have the
correct configure line.
Added a regex for version parsing as the R URLs are a little odd.

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

@@ -0,0 +1,15 @@
+from spack import *
+
+class RAbind(Package):
+    """Combine multidimensional arrays into a single array. This is a generalization of 'cbind' and 'rbind'. Works with vectors, matrices, and higher-dimensional arrays. Also provides functions 'adrop', 'asub', and 'afill' for manipulating, extracting and replacing data in arrays."""
+
+    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)
+
+    extends('R')
+
+    def install(self, spec, prefix):
+
+        R('CMD', 'INSTALL', '--library=%s' % self.module.r_lib_dir, '%s' % self.stage.archive_file)