Verify registry configuration on startup

[timburks]

Currently the registry configuration is read the first time it is needed, during handling of the first API request, which makes it difficult to handle configuration problems and also leads to race conditions if multiple requests are made before the configuration is read.

[theganyo]

@timburks Just FYI, I attempted to investigate this a while back because I thought it was be useful to be familiar with registry-viewer, but I couldn't get the build working in a reasonable timeframe so abandoned it.