include SignatureValidation filter with FileBackedHTTPMetadataProvider

[rdw at steadingsoftware.com]

> 
> . What am I missing?
> 

Well there’s an assumption that you own the security of your filesystem and hence cache.  So if it was safe when it was downloaded it’s still safe (or timed out in which case it won’t load for another reason). 

But even to be having this discussion you need to have turned off the signing check on restart which is only possible on the sp and only since very recently (2.6 ?)

/r