[CHEF-4748] ID validation for knife data bag creation

https://tickets.opscode.com/browse/CHEF-4748

This adds client-side validation of data bag IDs into knife during ```knife data bag create <name>``` (which is currently performed during ```knife data bag from file <name> <item>``` and ```knife data bag edit <name> <item>```).

We should either never or always do client side validation. See the situation that arrises without this patch in the ticket above.