"In Folder" constraints don't restore in exported Processor Filters

[gcdev373]

Processor Filters can be given a constraint <Feed> <InFolder> <Folder>

This works fine, and is exported as part of the processor filter.

However, if that processor filter is restored into a different Stroom instance, the processor filter fails to match any folders and on editing in the UI a warning is shown. This happens even when the folder that was referred to in the filter and the feeds contained in it are exported at the same time as the processor filter, and is due to the fact that folder uuids are not exported with the content itself.