Fix setuptools handling in Python packages.

- add setuptools dependencies to packages that need it.
- remove setuptools from packages that do not need it.

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

@@ -32,4 +32,5 @@ class PyBottleneck(PythonPackage):
 
     version('1.0.0', '380fa6f275bd24f27e7cf0e0d752f5d2')
 
+    depends_on('py-setuptools', type='build')
     depends_on('py-numpy', type=('build', 'run'))