Working for api's with more than one version

User has to define api_versions method in webservice_tester.rb initialize file.
This method is used in view to check if api has one or more versions, if the method returns an empty array, webservice_tester works as before, with no changes, and if the method returns an array with one or more elements, webservice_tester will add links for each version before the table with api methods.
The EXAMPLES constant has to be a hash if api has two or more versions, and the keys are the version names used in api_versions method.

ps: css is very ugly.