Database table descriptions

• causes: A list of ~100 causes with canonical names and possible aliases. Alias1 came from Philanthropy. Alias2 and Alias3 came from Charity Navigator. Alias4 and Alias5 came from Look to the Stars. Alias6 came from the Million Dollar Database.
• causes_nonprofits_rel: Many-to-many mapping between causes table and nonprofits table.
• causes_nonprofits_rel2: Many-to-many relations between nonprofits and causes taken from looktothestars. TODO: The cause homelessness has an extra character at the end that should be deleted.
• companies: Currently empty. Not sure why, this used to have data in it. On the other hand, we'd need to repopulate it with the Bloomberg list of companies anyway.
• nonprofit_twitter_attributes: Social network analysis attributes of the twitter accounts of the nonprofits.
• nonprofit_twitter_edges: Many-to-many relations between nonprofit twitter accounts with number of shared followers.
• nonprofit_websites: Nonprofits can have multiple websites (e.g., an official site, Facebook, and Twitter), so we store them in this one-to-many table.
• nonprofits: A list of ~2000 nonprofits. Some have EINs, some don't. Generated from merge_charities/union2.json on EC2, which is Look to the Stars charities combined with... some Charity Navigator charities? I think that was the intention, but it looks like it's just Look to the Stars charities.
• nonprofits_similarity_by_description: Couples of nonprofits and score determined by the similarity of their description taken from looktothestars.
• nonprofits_similarity_by_homepage: Couples of nonprofits and score determined by the similarity content of their homepages.
• nonprofits_similarity_by_tweets: Couples of nonprofits and score determined by the similarity of the content of their tweets.
• nonprofits_tweets: List of most recent tweets for all the nonprofits of which we have twitter handles. TODO: Change type of created_at attribute from string to date.
• nonprofits_users_rel: Table connecting the twitter accounts of the nonprofits to the ids of their followers.