Package env detects what sort of environment Perkeep is running in.
DebugUploads reports whether this is a debug environment for uploads.
IsDebug reports whether this is a debug environment.
IsDev reports whether this is a development server environment (devcam server).
OnGCE reports whether this process is running in a Google Compute Engine (GCE) environment. This only returns true if the "camlistore-config-dir" instance metadata value is defined. Instances running in custom configs on GCE will be unaffected.