raise more meaningful exceptions
rename method to match intention
list cmd should not eval guardfile
refactor runner
fix scoping when symbols are mixed with objs
stub out evaluator in ui
force specs to stub File and FileUtils
remove mostly unused fixtures
refactor setuper interactor specs
add dev comments (setuper)
prevent specs from touching fs
refactor dsl_spec + minor preparations

And:
- stop internally using deprecated method (since it will ultimately disappear)
- remove specs interacting with scope (scope will become an object)
fix dsl spec (file stubbing)
allow also spawning interactive guard in cucumber
add minor TODO
add interactive tests which require spawning