updated OS X installation instructions to Homebrew (which is more up-to-date and flexible these days); modular way to determine path to 'psql', 'createdb' and 'dropdb'
updated OS X installation instructions to Homebrew (which is more up-to-date and flexible these days); modular way to determine path to 'psql', 'createdb' and 'dropdb'

berkmancenter/mediacloud,AchyuthIIIT/mediacloud,AchyuthIIIT/mediacloud,AchyuthIIIT/mediacloud,berkmancenter/mediacloud,AchyuthIIIT/mediacloud,AchyuthIIIT/mediacloud,berkmancenter/mediacloud,AchyuthIIIT/mediacloud,berkmancenter/mediacloud,berkmancenter/mediacloud,AchyuthIIIT/mediacloud,AchyuthIIIT/mediacloud,AchyuthIIIT/mediacloud