WikiService needs to use the auth url if the endpoint is authenticated,
otherwise wikis which require authentication can never be gotten.
Fix the getContent method.
Adds the content of each page to the outputted JSON.
WIKI_PAGES now requires an authenticated NamedUrlPart.
Export Wiki sample updated to authenticated the endpoint first, and to
include tags.
Mock endpoint should return true for isAuthenticated.
getContent method should return content if it is present, otherwise make
the request.
Output image attributes as part of the sample.
No need to set user and password when using login
Fix copyright symbol
Add the isAuthenticated to the UrlBuilder format method, to reduce code
duplication.
Make the authenticated state in MockEndpoint configurable.
Merge pull request #1540 from fmoloney/wikiExportSample

Wiki Export sample Update