15: Add support for dynamic page titles

[cvburgess]

Adds optional support for setting the page title based on the breadcrumbs a user has defined.

Example:

<Breadcrumbs
  mappedRoutes={routes}
  titleFn={name => `MyApp - ${name}`}
/>

Closes #15

[almmiko]

Hi @cvburgess

Thanks for your PR. I will review it.

[cvburgess]

Thank you @roya3000

[cvburgess]

I noticed this solution does not seem to handle the rootName, so I would be happy to update that if you thought of a better solution.

[cvburgess]

Any update on this?