shared: do indent signature

These files are usually so small that it's free (< FS block size)
and it is more readable with non-str option values (possible with
slapos.buildout).

slapos/recipe/__init__.py

@@ -115,7 +115,7 @@ class Shared(object):
               if profile_base_location else v)
           for k, v in options.items()
           if k != '_profile_base_location_'
-        }, ensure_ascii=False, indent=0, sort_keys=True)
+        }, ensure_ascii=False, indent=2, sort_keys=True)
         if not isinstance(signature, bytes): # BBB: Python 3
           signature = signature.encode()
         digest = md5(signature).hexdigest()