erp5: add jedi egg

https://jedi.readthedocs.io/en/latest/
Jedi - an awesome autocompletion/static analysis library for Python

The initial idea is to use jedi for completions in ERP5 python editor
for scripts and components.

stack/erp5/buildout.cfg

@@ -517,6 +517,7 @@ eggs = ${neoppod:eggs}
   networkx
 # Needed for checking ZODB Components source code
   pylint
+  jedi
   pytracemalloc
   xlrd
 
@@ -828,3 +829,6 @@ responses = 0.10.6
 # Required by:
 # responses = 0.10.6
 cookies = 2.2.1
+
+jedi = 0.15.1
+parso = 0.5.1