use capnotify#delete_component in built-ins
added support for disabling default plugins

 - fixed tests around plugin loading by properly unloading all plugins
   after each test
 - wrap all trigger definitions inside on(:load) so that ordering
   matters less
 - set capnotify_disable_default_components to true to disable default
   plugins
added comments around deployer_username
removed unused capnotify_plugins cap var
components now have access back to the config

this is needed so the templates can have access to the full capistrano
environment
increased spacing between footer in html emails.
increased spacing in the <dl> in html view
wrap strings in a div.content tag to space out
fixed test with build!

needs to have a config passed to it.