Added export from search expression functionality to CLIUtils.

Also rearranged ordering in CLIUtils class so that import and export
are next to each other.
Fix export of multiple records.

Now also with progress bar!
Allow item-level export via CLI tool
Now cache BaseModel instances of exporters and exporter items.

They tend to be used over and over when dealing with record set exports
because the item hierarchy tree is traversed for each item to export.
This change cut the processing time in half.
Fix export context switch.

This still seems a bit hacky, because we have two different return
formats for the same function, depending on what we're doing. Probably
not the best thing.
Now use consistent return format for item processor function.

Seems a bit cleaner now (see problem mentioned in the previous commit).
Also removed test script that wasn't supposed to be committed in the
first place.