use rails rc1 instead of master branch
remove methods for default values from EmailNotifier class

These defaults_* methods made stuff more hard and complicated. For example, instead of this:

  :background_sections => %w(new_bkg_section) + ExceptionNotifier::EmailNotifier.default_background_sections

just do:

  :background_sections => %w(new_bkg_section backtrace data)
reorganize tests
split out rack middleware from exception notifier core
Drop compatibility with old configuration style

Since rack middleware is now called ExceptionNotification::Rack instead
of ExceptionNotifier, upgrading from previous versions requires changes.
Then when upgrading, users will also have to upgrade configuration
options hash.
add resque failure backend
add sidekiq support
add Rails generator to configure Resque/Sidekiq support

This generator create an initializer file within config code for support
Resque/Sidekiq.

Usage:

  rails generate exception_notification:install --resque

or

  rails generate exception_notification:install --sidekiq
add rails engine
improve rails initializer
update sinatra example
allows add multiple ignore conditions
remove residual logic from the rack middleware

Now, rack logic is added to global ignore conditions, avoiding
unexpected behavior when triggering exceptions manually -- like this
rack middleware.

Closes #159
load rails engine only in initializer

avois add rake middleware twice, if it is already added as rack
middleware.
add logger
fix rack env variable 'exception_notifier.delivered'
update changelog
Be able to override delivery_method

Close #161
Change readme to more explicit documentation directions
update docs