Remove hashtag column. Fixes #4

I don't people who are going to look at this are going to care about the hashtags of hackathons. They'll just go to the hackathon, which will advertise the twitter hashtag themselves. Also:

- Very few hackathons post their hashtags online (if they have one)
- Hashtags aren't as popular with hackathons as opposed to devconfs.
Merge pull request #7 from grant/patch-2

Remove hashtag column. Fixes #4