Incorporate list of known Reddit bots into data cleaning

[divilian]

1. Get the list.
2. Add code to the get_thread() method of classifier.py to skip if the author is on the list (get assist from @TromboneDavies if necessary).
3. Figure out what to do about "users who have 'bot' in their name," if anything. (Search for the standard "I am a bot" language?) Run your decision by the rest of the team. See Soliman paper, p.260.

[akochans]

botnames.csv added to classifier directory