Tried to make the "get tweets" function more versatile

I wanted to be able to include the tweets.php file in any other php file and use the function inside of it to grab tweet data without displaying it, for use later.

I also wanted to be able to keep tweets.php up to date via GitHub without it overwriting any of my "settings", so I turned all the variables into an array of parameters.

This version requires that you do something like:

    include('latest-tweets-php-o-auth/tweets.php');
    echo get_latest_tweets(array('twitter_user_id'=>'twitter'));

I also added a handful of .gitignore rules, removed .DS_Store, etc.