spigots: Fix manual proxy settings to be spec compliant

ProxyLocation was previously using the key 'URL' but should have been
using 'Host'.  I recently changed the key name to reflect that manual
proxy settings are just to (host,port) pairs vs URLs (as Proxy
Auto-config uses).

Change-Id: Ifb0b4262f6ce551473da63d71d3375529f260914
4 files changed