Merge branch 'mplegendre-multi_pkgsrc_roots' into develop

- This moves var/spack/packages to var/spack/repos/builtin/packages.

- Packages that did not exist in the source branch, or were changed in
  develop, were moved into var/spack/repos/builtin/packages as part of
  the integration.

Conflicts:
	lib/spack/spack/test/unit_install.py
	var/spack/repos/builtin/packages/clang/package.py

var/spack/repos/builtin/packages/py-setuptools/package.py

@@ -0,0 +1,16 @@
+from spack import *
+
+class PySetuptools(Package):
+    """Easily download, build, install, upgrade, and uninstall Python packages."""
+    homepage = "https://pypi.python.org/pypi/setuptools"
+    url      = "https://pypi.python.org/packages/source/s/setuptools/setuptools-11.3.tar.gz"
+
+    version('11.3.1', '01f69212e019a2420c1693fb43593930')
+    version('16.0', '0ace0b96233516fc5f7c857d086aa3ad')
+    version('18.1', 'f72e87f34fbf07f299f6cb46256a0b06')
+    version('19.2', '78353b1f80375ca5e088f4b4627ffe03')
+
+    extends('python')
+
+    def install(self, spec, prefix):
+        python('setup.py', 'install', '--prefix=%s' % prefix)