update rspec for the appraisals
no need to module_eval - simply call autoload on the module
support setting a "relative url root" even with plain rack applications
for now needs to be explicitly configured with rack.relative_url_root_variable
review Railtie for setting relative_url_root - do not override if already set ...
- Rails defaults config.relative_url_root to ENV['RAILS_RELATIVE_URL_ROOT']
- if user set something explicit in the environment it will now be kept
(we're setting config.action_controller.relative_url_root only if config.relative_url_root has not been set)
appraise latest once again - move apprasisal gem to development group
[travis-ci] run `rake spec` and bundle --without development
always force BUNDLE_GEMFILE for the "mock" rails apps + print warnings
isolate ENV correctly (esp. due travis-ci)