Implement review requests

- use two empty lines before `class`
- change version numbering scheme for packages, use `url_for_version` to make things work
- specify dependency types
- add comment about temporarily moved download location
- update two packages to newer versions

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

@@ -25,6 +25,7 @@
 
 from spack import *
 
+
 class Sympol(Package):
     """SymPol is a C++ tool to work with symmetric polyhedra"""
     homepage = "http://www.math.uni-rostock.de/~rehn/software/sympol.html"