Introduce consistent convention for ValueConverter binding

Introduce consistent convention of binding converters.

All bind error error keys should start with "bind.error." followed by the type (eg number, date, list) and additionally other qualifiers (eg bind.error.date.missing).

All configurable values (eg binding errors or formats) should also have default values defined in the ValueConverter (no additional configuration should be necessary to receive a meaningful result). All keys used (with default values) should be documented in javadoc and http://waffle.codehaus.org/binding.html web page.