Removed trailing white space & Fixed typo in StaticDirectoryContent & StaticFileContent 

Originally I was just going to fix a typo & and [make {} on it's own line](https://github.com/NancyFx/Nancy/blob/master/src/Nancy/Bootstrapper/MultipleRootPathProvidersLocatedException.cs#L25) but then I noticed the trailing white space because I had trailing whitespace visualizer  extension on in visual studio so I decided to clean some of it up. Not going to lie, I completely skipped the JSON folder however.