Add options to spare tweets

[boyvanamstel]

Adds the option to spare tweets by their id_str, favorite_count or retweet_count.

[valenzine]

I tried to use this version and I get:

valenzine$ python deletetweets.py -d 2012-01-01 tweet.js --spare-min-likes 10 --spare-min-retweets 5
Traceback (most recent call last):
  File "deletetweets.py", line 112, in <module>
    main()
  File "deletetweets.py", line 108, in main
    delete(args.file, args.date, args.restrict, args.spare_ids, args.min_likes, args.min_retweets)
  File "deletetweets.py", line 77, in delete
    for row in TweetReader(tweets, date, r, s, min_l, min_r).read():
  File "deletetweets.py", line 56, in read
    if row.get("id_str") in self.spare:
TypeError: argument of type 'NoneType' is not iterable

[boyvanamstel]

@valenzine Thanks for reporting this. The --spare-ids argument defaults to NoneType instead of an empty array. The last commit resolves the issue.

[valenzine]

Awesome! Will check it out. Thanks!

[koenrh]

@boyvanamstel Thank you, this is a great addition! I'll merge it later today.

[boyvanamstel]

You're welcome Koen. Thanks :)