Fix initializing OrgNode level to string to parse org files

- Parsed `level` argument passed to OrgNode during init is expected to
  be a string, not an integer
- This was resulting in app failure only when parsing org files with
  no headings, like in issue #83, as level is set to string of `*`s
  the moment a heading is found in the current file

src/processor/org_mode/orgnode.py

@@ -61,7 +61,7 @@ def makelist(filename):
 
    todos         = { "TODO": "", "WAITING": "", "ACTIVE": "",
                      "DONE": "", "CANCELLED": "", "FAILED": ""} # populated from #+SEQ_TODO line
-   level         = 0
+   level         = ""
    heading       = ""
    bodytext      = ""
    tags          = set()      # set of all tags in headline