Support Windows registry arrays as a REG_MULTI_SZ string

[ericpromislow]

containerEngine.allowedImages.patterns is currently not being read.

And there are no docs on how to express this in the registry.

[ericpromislow]

Other things to do:

1. Use a boolean to indicate whether there's an HKLM profile. The test right now always succeeds
2. Registry values are picked up but not returned, so they don't show up in the settings object or file.