Fix taskwarrior hook when tags are numeric values

When tags are numeric (ex: `3148`) the hook fails, because timewarrior treats it as a time value.

The above change prepends `#` to all numeric tags, so that timewarrior will be triggered by taskwarrior correctly when using numeric only tags (for example: issue ids automatically fetched with bugwarrior).

on_modify.py

@@ -55,9 +55,14 @@ def extract_tags_from(json_obj):
             # Usage of tasklib (e.g. in taskpirate) converts the tag list into a string
             # If this is the case, convert it back into a list first
             # See https://github.com/tbabej/taskpirate/issues/11
-            tags.extend(json_obj['tags'].split(','))
+            tag_list = json_obj['tags'].split(',')
         else:
-            tags.extend(json_obj['tags'])
+            tag_list = json_obj['tags']
+
+        for i in range(len(tag_list['tags'])):
+            if tag_list['tags'][i].isnumeric():
+                tag_list['tags'][i] = '#' + tag_list['tags'][i]
+        tags.extend(tag_list['tags'])
 
     return tags