Added a showUrlWhileLoading BOOL property to prevent showing the URL while the page is loading.
I'm building an app where the initial URL is always redirected to something else (kind of like clicking on a bit.ly link). It is desirable to hide the initial URL in this scenario, since it is never the final URL.
Merge pull request #8 from melsam/make-loading-url-optional

Make the URL optional when loading a page.