Make spec errors more informative

[Strech]

  2) Api::V2::UsersController updates a user surname as string
     Failure/Error: Unable to find matching line from backtrace
     Lurker::UndocumentedResponseCode:
       Undocumented response: 200, successful: true
     # /media/psf/Develop/github/lurker/lib/lurker/json/schema/response_codes.rb:23:in `validate!'
     # /media/psf/Develop/github/lurker/lib/lurker/endpoint.rb:78:in `consume_response'
     # /media/psf/Develop/github/lurker/lib/lurker/endpoint.rb:58:in `consume!'
     # /media/psf/Develop/github/lurker/lib/lurker/service.rb:49:in `verify!'
     # /media/psf/Develop/github/lurker/lib/lurker/spy.rb:29:in `block in call'
     # /media/psf/Develop/github/lurker/lib/lurker/spy.rb:27:in `tap'
     # /media/psf/Develop/github/lurker/lib/lurker/spy.rb:27:in `call'
     # /media/psf/Develop/github/lurker/lib/lurker/spy.rb:79:in `on'
     # /media/psf/Develop/github/lurker/lib/lurker/spec_helper/rspec.rb:17:in `block (2 levels) in <top (required)>'
     # /root/.rbenv/versions/2.2.0/lib/ruby/gems/2.2.0/gems/rspec-core-2.14.8/lib/rspec/core/extensions/instance_eval_with_args.rb:16:in `instance_exec'
     # /root/.rbenv/versions/2.2.0/lib/ruby/gems/2.2.0/gems/rspec-core-2.14.8/lib/rspec/core/extensions/instance_eval_with_args.rb:16:in `instance_eval_with_args'
     # /root/.rbenv/versions/2.2.0/lib/ruby/gems/2.2.0/gems/rspec-core-2.14.8/lib/rspec/core/example.rb:247:in `instance_eval_with_args'
     # /root/.rbenv/versions/2.2.0/lib/ruby/gems/2.2.0/gems/rspec-core-2.14.8/lib/rspec/core/hooks.rb:106:in `block (2 levels) in run'
     # /root/.rbenv/versions/2.2.0/lib/ruby/gems/2.2.0/gems/rspec-core-2.14.8/lib/rspec/core/hooks.rb:108:in `call'
     # /root/.rbenv/versions/2.2.0/lib/ruby/gems/2.2.0/gems/rspec-core-2.14.8/lib/rspec/core/hooks.rb:108:in `run'
     # /root/.rbenv/versions/2.2.0/lib/ruby/gems/2.2.0/gems/rspec-core-2.14.8/lib/rspec/core/hooks.rb:446:in `run_hook'
     # /root/.rbenv/versions/2.2.0/lib/ruby/gems/2.2.0/gems/rspec-core-2.14.8/lib/rspec/core/example_group.rb:340:in `run_around_each_hooks'
     # /root/.rbenv/versions/2.2.0/lib/ruby/gems/2.2.0/gems/rspec-core-2.14.8/lib/rspec/core/example.rb:256:in `with_around_each_hooks'
     # /root/.rbenv/versions/2.2.0/lib/ruby/gems/2.2.0/gems/rspec-core-2.14.8/lib/rspec/core/example.rb:111:in `run'
     # /root/.rbenv/versions/2.2.0/lib/ruby/gems/2.2.0/gems/rspec-core-2.14.8/lib/rspec/core/example_group.rb:390:in `block in run_examples'
     # /root/.rbenv/versions/2.2.0/lib/ruby/gems/2.2.0/gems/rspec-core-2.14.8/lib/rspec/core/example_group.rb:386:in `map'
     # /root/.rbenv/versions/2.2.0/lib/ruby/gems/2.2.0/gems/rspec-core-2.14.8/lib/rspec/core/example_group.rb:386:in `run_examples'
     # /root/.rbenv/versions/2.2.0/lib/ruby/gems/2.2.0/gems/rspec-core-2.14.8/lib/rspec/core/example_group.rb:371:in `run'
     # /root/.rbenv/versions/2.2.0/lib/ruby/gems/2.2.0/gems/rspec-core-2.14.8/lib/rspec/core/command_line.rb:28:in `block (2 levels) in run'
     # /root/.rbenv/versions/2.2.0/lib/ruby/gems/2.2.0/gems/rspec-core-2.14.8/lib/rspec/core/command_line.rb:28:in `map'
     # /root/.rbenv/versions/2.2.0/lib/ruby/gems/2.2.0/gems/rspec-core-2.14.8/lib/rspec/core/command_line.rb:28:in `block in run'
     # /root/.rbenv/versions/2.2.0/lib/ruby/gems/2.2.0/gems/rspec-core-2.14.8/lib/rspec/core/reporter.rb:58:in `report'
     # /root/.rbenv/versions/2.2.0/lib/ruby/gems/2.2.0/gems/rspec-core-2.14.8/lib/rspec/core/command_line.rb:25:in `run'
     # /root/.rbenv/versions/2.2.0/lib/ruby/gems/2.2.0/gems/rspec-core-2.14.8/lib/rspec/core/runner.rb:80:in `run'
     # /root/.rbenv/versions/2.2.0/lib/ruby/gems/2.2.0/gems/rspec-core-2.14.8/lib/rspec/core/runner.rb:17:in `block in autorun'

• Change trace?
• Fix Failure/Error: Unable to find matching line from backtrace