Developer guide and seed

Since it took me sometime to catch myself up to even start developing, I decided to add a guide to help get the user up and started.  I also added the db/seeds.rb file to allow users to do: rake db:seed to actually have a couple of pre-gen users in the database.  Probably in the future we should add some sample tweets to start out, so that a developer can have some sample data even to work with.