Make IceBox watcher report more reliable

[zivkan]

• Fix IceBoxResource.resx, so it can build on Linux
• Retry failed HTTP requests up to 5 times
• When a failed response has a Retry-After header, respect the duration
• Output to the console the failed HTTP response headers and body, so we can see what the failure is

Turns out the errors we were seeing were reaching github's secondary rate limit