preserving header case broke response content type
upgrade wicket to 6.7.0
factor out jetty version
factor out spring version
render joda time in ui

this shows milliseconds and timezone without needing
explicit converter.
add interfaces to services
rename ITapRequestDao to ITapExchangeDao
get wicket jiunit test working

the trick here is to get an application context
into the onComponentInstantiationListener both
when started from web.xml and when started from junit test.
See wicketApplication.java.
add ExchangePageTest