Fix swagger example stubbing

[fishermand46]

I was getting a few errors when trying to stub requests against a swagger contract that had examples.

First off, the Swagger::ResponseClause did not have a to_hash method defined, so it was throwing an error here.

Secondly, the Webmock was complaining because the stubbed response body was being set to a Swagger::V2::Example object, instead of a string. I fixed this by calling parse on the example object before setting it in the response hash.

[coveralls]

Changes Unknown when pulling 2bd52fb on fishermand46:fix_pacto_example_stubbing into * on thoughtworks:master*.