SimpleDateFormat-s should be created with Locale defined in constructor

The wicket-core junit test o.a.w.util.time.TimeTest.test() fails on computers where the default locale strings for "Am/pm marker" is not am/pm. The reason for this is that wicket uses SimpleDateFormat(String pattern) constructor instead of SimpleDateFormat(String pattern, Locale locale) in a lot of places and so the system default locale is used.

I think for consistent results wicket should always specify a locale and not depend on the system default.