Comment 1 for bug 1741072

The simple fix for this is to add a new directive to the ui service to convert the model from a number to a string. Since this kind of thing has come up in previous bugs (bug 1713064 and bug 1714390, which conflicted with bug 1712646 because a similar but not identical fix is required) I plan to address it by adding 2 pairs of symmetric directives to the shared egUiMod module; str-to-int and int-to-str, and str-to-float and float-to-str. Additionally the current uses of string-to-number in staff/cat/volcopy/app.js will be converted to the appropriate shared directive and the old string-to-number will be removed.