js: home: Decode url portion of url get parameter

[michaelwood]

When receiving the url get parameter decode the url before internally submitting the "fetch from url" form. This allows us to send the url correctly url encoded whilst still maintaining backward compatibility with old urls.

e.g. https://insights.threesixtygiving.org/?url=https://grantnav.threesixtygiving.org/search.json?query=%2A&default_field=%2A&sort=_score+desc&amountAwarded=10000000 vs https://insights.threesixtygiving.org/?url=https://grantnav.threesixtygiving.org/search.json%3Fquery%3D%2522test%2Bvalley%2522%26default_field%3D%252A%26sort%3D_score%2Bdesc

[michaelwood]

@Bjwebb Merged & now deployed