Use OkHTTP instead of my home-made HTTP, for network validation.

The home-made version was only done because there was no previous way to
perform network-specific HTTP.  The home-made version has already shown
incompatibility, see linked bug.

bug:16316314
Change-Id: Ic9e50174552d1466eb1ff59ff9d28e18035cc3e0
1 file changed