Regex soft-retweet detection

I added a regex to detect 'RT @' anywhere in the content of a tweet, in
case someone hides a RT in the middle of a tweet! As a bonus, it also
detects a bunch of different types of quotes as well as other things
people might use, like 'via,' 'by,' and 'from'!
Switched to .match for matching

Mispy taught me something about ruby precedence today!
Merge pull request #41 from Stawberri/regex_rt

Regex soft-retweet detection