Cannot un-set ldap.password to return to anonymous bind

For various reasons, I have Crowd set up to do anonymous bind. That's fine, until Firefox does an autofill (Firefox's auto-fill seems to have become more aggressive since the field-rename in CWD-599). I can remove the ldap.userdn but not the ldap.password — a blank password apparently means "don't modify". To fix this, I have to poke the database (good thing I'm not using HSQLDB).

Moreover, in addition to losing the password (CWD-1763), the "test connection" button also uses the password in the field instead of the one in the database. This means the "Test Connection" button will fail where it would otherwise succeed.

A simple (if slightly horrible) solution would be to treat ******** as a string meaning "whatever is in the database". This means it's impossible to set the password to eight asterisks, but that's something we can live with. It also means the "test connection" button can know when it has to pull the password out of the database.

Not quite sure which component this goes in; it's largely a UI problem.