0.3.0

• Add code documentation and improve exception message
• Add whitelisting of bot ids in the configuration through whitelisted_bot_ids=
• Refactored Handler configuration into Slackify::Router and Slackify::Handlers::Factory
• Improved testing
• Remove the need to perform Slackify.load_handler
• Breaking change: Given that we now load the handlers on Slack.configure, the configuration step done in config/application.rb will have to be done in an initializer to have all the handler class loaded.