Small fixes for newpatient.form

In the newpatient.form , a few requests:

1. At least one identifier is required, so the remove button should not be shown when only one Identifier coloumn is present.
2. Also If there is something wrong with the submission at this page, It automatically adds one more row for Identifier.

How to reproduce the second bug: From the shot patient form, add a new identifier and leave it invalid e.g by not setting the type, submit the form, it should come back with errors, then remove the identifier with errors and add a new valid identifier and resubmit the form. This should be valid but the form is displayed again because the previous new identifier that had errors wasn't actually removed.