Bug 1037237: Support for UltraVNC on Windows; r=dustin
Bug 1040584: Custom Windows MSI Provider; r=dustin
Bug 1022763: configure mockbuild from runner

This configures mockbuild based on the location of the node, but in such
a way that puppet is not required.  Instead the configuration is based
on the placement/availability-zone instance metadata, and if that is
empty (e.g., in-house), then uses the public vhost,
mockbuild-repos.pub.build.mozilla.org.