Add spack packages for tvb-framework dependencies that are not available on spack

Spack packages are not available for some of the dependencies of tvb-framework package: pyAesCrypt and formencode. I am adding here the spack files for them, so we can have all tvb-framework functionalities available in the Lab.

packages/formencode/package.py

+# Copyright 2013-2020 Lawrence Livermore National Security, LLC and other
+# Spack Project Developers. See the top-level COPYRIGHT file for details.
+#
+# SPDX-License-Identifier: (Apache-2.0 OR MIT)
+
+from spack import *
+
+
+class Formencode(PythonPackage):
+    """
+    Requirement necessary for tvb-framework package.
+    """
+
+    homepage = "https://pypi.org/project/FormEncode"
+    pypi = 'FormEncode/FormEncode-2.0.0.tar.gz'
+
+    maintainers = ['paulapopa']
+
+    version('2.0.0', 'f2eb92297417eb64e4aa8e368783a5ac1311e385d4f3ff3a181090608ea83711')
+
+    # python_requires
+    depends_on('python@3.8:', type=('build', 'run'))
+
+    # setup_requires
+    depends_on('py-pip', type=('build'))
+    depends_on('py-setuptools', type=('build', 'run'))
+    depends_on('py-six', type='run')