Add package for aspell and ass't dictionaries (#3890)

* Add package for aspell and ass't dictionaries

Add a package definition for aspell.

Add a handful of dictionaries to convince myself that the support for
a bunch of dictionaries works.

* Flake8 cleanup

* Use six's version of urlparse

`urlparse` is not python3 friendly.  This works around it (stolen from
`.../cmd/md5.py`).

* Fix incorrect trimming regexp

* Clean up dictionary build

- more parsimonious use of `which` (`make()` has already been made)
- use `sh` instead of `bash`

* Use a helper method to generate info for variants

I figured out my issues with static methods.  I *think* that it this
is pythonic.

* Convert aspell to an extendable package

Convert aspell to be extendable and rework the dictionaries to be
extensions.

As it stands, there's a great deal of cut and paste in the
dictionaries, I'll abstract that out next.

The {de,}activate methods copy a great deal of code out of
package.py.  Perhaps there's a better way....

* Create AspellDictPackage and use it for the dictionaries

Reduce the repeated code, pull it into a base class.

I'm confused about why 'from spack import *' wasn't more useful in the
base class.

* Oops, -de & -es should be AspellDictPackages too

* Typo: pakcage -> package

* Address some commentary

* Update copyright dates, 2016->2017

var/spack/repos/builtin/packages/aspell6-de/package.py

@@ -0,0 +1,34 @@
+##############################################################################
+# Copyright (c) 2013-2017, Lawrence Livermore National Security, LLC.
+# Produced at the Lawrence Livermore National Laboratory.
+#
+# This file is part of Spack.
+# Created by Todd Gamblin, tgamblin@llnl.gov, All rights reserved.
+# LLNL-CODE-647188
+#
+# For details, see https://github.com/llnl/spack
+# Please also see the NOTICE and LICENSE files for our notice and the LGPL.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License (as
+# published by the Free Software Foundation) version 2.1, February 1999.
+#
+# This program is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the IMPLIED WARRANTY OF
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the terms and
+# conditions of the GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with this program; if not, write to the Free Software
+# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+##############################################################################
+from spack import *
+
+
+class Aspell6De(AspellDictPackage):
+    """German (de) dictionary for aspell."""
+
+    homepage = "http://aspell.net/"
+    url      = "ftp://ftp.gnu.org/gnu/aspell/dict/de/aspell6-de-20030222-1.tar.bz2"
+
+    version('6-de-20030222-1', '5950c5c8a36fc93d4d7616591bace6a6')