Add ability to run AdHere on any URL from the frontend dashboard

[KShervington]

Currently, when using the dashboard, users can only run AdHere on the provided list of sites that have recently violated the Better Ads Standard.

Users should have the ability to run AdHere on any URL they desire, from the dashboard. This is more akin to the original design of AdHere, which allowed users to provide any URL as an argument, when running AdHere from a terminal.

This could be accomplished by adding a text box somewhere for users to type the URL they want to run AdHere against.