Added clear context
Added clear context

The crumb trail key was retained across unit tests. The different
StateInfo meant the old key wasn't valid. Good idea to clear context for
server rendering although navigateLink effectively clears context (if
add old State and Data to context then this will need clearing on the
server)

grahammendick/navigation,grahammendick/navigation,grahammendick/navigation,grahammendick/navigation,grahammendick/navigation,grahammendick/navigation,grahammendick/navigation