Moved 20-tweet test files into test subdir inside tweetfiles. Created new function that gets last 400 tweets from a given user by id.
Removed duplicate get_timeline function, added 'count' parameter to specify number of tweets to get
Added 400 as count parameter to seed.py. Gets and writes 400 tweets per file.
Created 6 test files with up to 400 tweets each for 5 celebrity political figures.