UP-4290 add getAlternativeMaximizedLink() to IPortletDefinition.
UP-4291 getRenderUrl() is alternativeMaximizedLink when exists.
Refactor : Use syntactic sugar to get alternative maximized link.
Merge pull request #463 from apetro/UP-4291

UP-4291 MarketplacePortletDefinition renderUrl is alternativeMaximizedLink when available.