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/ninja/package.py

@@ -0,0 +1,22 @@
+from spack import *
+import os
+
+class Ninja(Package):
+    """ A small, fast Make alternative """
+    homepage = "https://martine.github.io/ninja/"
+    url      = "https://github.com/martine/ninja/archive/v1.6.0.tar.gz"
+
+    version('1.6.0', '254133059f2da79d8727f654d7198f43')
+
+    extends('python')
+
+    def install(self, spec, prefix):
+        sh = which('sh')
+        python('configure.py', '--bootstrap')
+
+        cp = which('cp')
+
+        bindir = os.path.join(prefix, 'bin')
+        mkdir(bindir)
+        cp('-a', '-t', bindir, 'ninja')
+        cp('-ra', 'misc', prefix)