Use a valid name for new screener form

[earth-walker]

When I create a new screener, the name of the screener in the form editor always starts as "BDT Form", which is invalid because it contains a space. I don't know if this affects any functionality in the app or screener, but it's not a good look at the very least. Let's change it to something like "BDT_Form" to make it valid.