Add subparser to utils

[MichaelCurrin]

Change from argparser groups to argparse subparser

• [x] utils/insert/fetchProfiles.py
• [x] utils/insert/fetchTweets.py
• [ ] utils/manage/campaigns.py
• [ ] utils/manage/categories.py

The manage utils are simple enough to stay with the group approach, but it would be good for consistency to use the same approach for all.