Update new post script for new tagging format

new_post.py

@@ -1,6 +1,5 @@
-#!/usr/bin/env python
+#!/usr/local/bin/python3
 import datetime
-import yaml
 
 blog_title = input('title for the entry: ')
 title_date = input('date for the entry (format:yyyy-mm-dd|defaults to today): ')
@@ -20,16 +19,14 @@ layout: post
 title: "go: `:=` operator causes accidental shadowing"
 date: 2016-01-14 21:13
 comments: true
-categories:
-  - go
+tags: tag1, tag2..
 '''
 metadata_fmt = """---
 layout: post
 title: "{}"
 date: {}
 comments: true
-categories:
-{}
+tags: {}
 ---
 """
 catblock = "  - {}"
@@ -39,7 +36,7 @@ cats = map(catblock.format, tags.split())
 metadata_fmt = metadata_fmt.format(
    blog_title,
    title_date,
-   '\n'.join(cats)
+   ', '.join(cats)
 )
 
 with open('blog/{}'.format(filename), 'w') as f: