Updated seed_tweets script to capture nonpolitical tweets and store in database.

 - Removed references to scoring
 - Added list of NONPOLITICAL_HASHTAGS at top of file to loop through in main()
 - Commented out insertion of hashtags into the database -- avoiding collecting additional hashtags for now, to keep political hashtags separate (although this could also be done through relationship between political tweets and hashtags)
 - Imported SQLAlchemyError, the base class for errors. When SQLAlchemy error exception reached, simply pass to continue processing tweets.
Add string of hashtags to EXCLUDE from twitter query, based on human evaluation of spammy hashtags. Add "#tbt" and "#ff" streams (3000 tweets each) to database while excluding spam hashtags.

 - Deleted 6000 spammy tweets from database
 - Now back at original number of data records, while excluding spam hashtags
 - 23,000 rows in statuses table
Removed scratch directory from git cache, since these are my private test files.