Spreadsheet loader collection selection warning message

[sarahjeansweeney]

A user new to the upload process for spreadsheets entered a handle instead of a pid when setting the collection for a spreadsheet upload. When he tried to submit the load, he got the following message:

Please select a destination collection from the dropdown.

That message is probably borrowed from the IPTC loader. It should be updated for the spreadsheet loader, something like

Please enter a valid collection PID

or something like that.

[dgcliff]

Yep, that looks legacy. I'll make a patch