Updates for tvb packages

Add specs in spack.yaml. Update names for pyaescrypt and formencode and specify them as dependencies for tvb-framework.

packages/py-formencode/package.py

@@ -6,7 +6,7 @@
 from spack import *
 
 
-class Formencode(PythonPackage):
+class PyFormencode(PythonPackage):
     """
     Requirement necessary for tvb-framework package.
     """