Add new query string parameter to filter on AS/partner/network

[nkinkade]

As we being to deploy infrastructure in different environments, we will likely come across network providers that would like to host their own portal/client that will guarantee (or at least have a high likelihood of) testing against the servers they host.

A case in point is CENIC. They are happy to have the majority of traffic use normal Locate Service distribution/load-balancing, both from within or outside of their network. However, they would also like to host their own testing portal which is more or less guaranteed to test against one of the sites they might host.

Today, the only way this might be possible is to leverage the ?site=<site> query parameter to Locate, possibly specifying it multiple times, in the case that they host multiple measurement sites.

It seems like it would be a useful enhancement to to be able to filter Locate results on a particular network provider. This could be something like AS number(s), or possibly a string representing the provider (e.g., calren, cenic, etc.)