Fix scenario

We need to use the pretty formatter because we're now actually handling
and printing the before hook exception in the formatter, where Cucumber
1.x was just throwing the exception and stopping Cucumber in its tracks.

Progress formatter doesn't print exception messages (though perhaps it
should?) so we need to use pretty.

features/docs/wire_protocol.feature

@@ -325,14 +325,13 @@ Feature: Wire Protocol
   #
   # # Bad Response
   #
-  @wip
   Scenario: Unexpected response
     Given there is a wire server running on port 54321 which understands the following protocol:
       | request                                              | response                            |
       | ["begin_scenario"]                                   | ["yikes"]                           |
       | ["step_matches",{"name_to_match":"we're all wired"}] | ["success",[{"id":"1", "args":[]}]] |
-    When I run `cucumber -f progress`
-    Then the stderr should contain exactly:
+    When I run `cucumber -f pretty`
+    Then the stdout should contain:
       """
       undefined method `handle_yikes'
       """