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/activeharmony/package.py

@@ -0,0 +1,15 @@
+from spack import *
+
+class Activeharmony(Package):
+    """Active Harmony: a framework for auto-tuning (the automated search for values to improve the performance of a target application)."""
+    homepage = "http://www.dyninst.org/harmony"
+    url      = "http://www.dyninst.org/sites/default/files/downloads/harmony/ah-4.5.tar.gz"
+
+    version('4.5', 'caee5b864716d376e2c25d739251b2a9')
+
+    def install(self, spec, prefix):
+        make("CFLAGS=-O3")
+        make("install", 'PREFIX=%s' % prefix)
+
+from spack import *
+