New, cleaner package repository structure.

Package repositories now look like this:

    top-level-dir/
        repo.yaml
        packages/
            libelf/
                package.py
            mpich/
                package.py
            ...

This leaves room at the top level for additional metadata, source,
per-repo configs, indexes, etc., and it makes it easy to see that
something is a spack repo (just look for repo.yaml and packages).

var/spack/repos/builtin/packages/ompss/package.py

@@ -0,0 +1,50 @@
+from spack import *
+import os
+import glob
+
+# working config lines for ompss 14.06 :
+#./nanox-0.7/config.log:    $ ./configure --prefix=/usr/gapps/exmatex/ompss --with-mcc=/usr/gapps/exmatex/ompss/ --with-hwloc=/usr
+#./mcxx-1.99.2/config.log:    $ ./configure --prefix=/usr/gapps/exmatex/ompss --with-nanox=/usr/gapps/exmatex/ompss --enable-ompss --with-mpi=/opt/mvapich2-intel-shmem-1.7 --enable-tl-openmp-profile --enable-tl-openmp-intel
+
+class Ompss(Package):
+    """OmpSs is an effort to integrate features from the StarSs
+       programming model developed by BSC into a single programming
+       model. In particular, our objective is to extend OpenMP with
+       new directives to support asynchronous parallelism and
+       heterogeneity (devices like GPUs). However, it can also be
+       understood as new directives extending other accelerator based
+       APIs like CUDA or OpenCL. Our OmpSs environment is built on top
+       of our Mercurium compiler and Nanos++ runtime system."""
+    homepage = "http://pm.bsc.es/"
+    url      = "http://pm.bsc.es/sites/default/files/ftp/ompss/releases/ompss-14.10.tar.gz"
+    list_url = 'http://pm.bsc.es/ompss-downloads'
+
+    version('14.10', '404d161265748f2f96bb35fd8c7e79ee')
+
+    # all dependencies are optional, really
+    depends_on("mpi")
+    #depends_on("openmp")
+    depends_on("hwloc")
+    depends_on("extrae")
+
+    def install(self, spec, prefix):
+        if 'openmpi' in spec:
+            mpi = spec['openmpi']
+        elif 'mpich' in spec:
+            mpi = spec['mpich']
+        elif 'mvapich' in spec:
+            mpi = spec['mvapich']
+
+        openmp_options = ["--enable-tl-openmp-profile"]
+        if spec.satisfies('%intel'):
+            openmp_options.append( "--enable-tl-openmp-intel" )
+
+        os.chdir(glob.glob('./nanox-*').pop())
+        configure("--prefix=%s" % prefix, "--with-mcc=%s" % prefix, "--with-extrae=%s" % spec['extrae'].prefix, "--with-hwloc=%s" % spec['hwloc'].prefix)
+        make()
+        make("install")
+
+        os.chdir(glob.glob('../mcxx-*').pop())
+        configure("--prefix=%s" % prefix, "--with-nanox=%s" % prefix, "--enable-ompss", "--with-mpi=%s" % mpi.prefix, *openmp_options)
+        make()
+        make("install")