#3 Finish Parameters support

[Juanjo]

On the main() method call:
ParametersUtil.CreateDefaultParameters()
http://punch-clock.svn.sourceforge.net/viewvc/punch-clock/trunk/client/PunchClockStation/src/org/punchclock/station/util/ParametersUtil.java?view=log&pathrev=189

2.- Put on ContextVars the new parameter messageBrokerURL

3.- When the Preferences Form or View is open fill the two fields, stationID and broker from the ContextVars.

4.- if the user press ok button, check if the form field is different from the contextVars, if it's true, update the DB, and the ContextVars.