uses_path_versioning? should return a bool

as stated on the test
https://github.com/arthurnn/grape/blob/01f2590741120b613a19a57836c2e05608ac586b/spec/grape/path_spec.rb#L60
that method should return +true+ or +false+
Use be false instead of be_false
Use be true instead of be_true
Merge pull request #588 from arthurnn/rspec_warn_update

Rspec boolean methods update