Extending the ContentTypeElement to include optional RuntimePolicy

[avanderhoorn]

When defining a ContentType for the ContentTypePolicy you should also be able to specify the RuntimePolicy that will be used if that ContentType is matched. This would allow users to specify that other non html types can be tracked by Glimpse fairly easily - see the following as a use case - http://stackoverflow.com/questions/21789069/show-file-download-in-glimpse.

So make this change, you can simply update the following config element https://github.com/Glimpse/Glimpse/blob/master/source/Glimpse.Core/Configuration/ContentTypeElement.cs set its default to RuntimePolicy.On and update https://github.com/Glimpse/Glimpse/blob/master/source/Glimpse.Core/Policy/ContentTypePolicy.cs to take it into account.