#101 made DefaultNavigatorExceptionHandler a Singleton
#101 made DefaultNavigatorExceptionHandler an observable for DefaultNavigatorExceptionHandlerListeners
#101 created ExceptionNotificationStatusPanel
#101 added ExceptionNotificationStatusPanel to the MutableStatusBar
#101 show the hand cursor also if the error icon is blinking
#101 hide the icon after the error dialog was closed. Changed the basic message.
#101 removed the method anErrorOccurred() as it was only a wrapper for uncaughtException() without any additional benefit
#101 javadoc
#101 changed a string and changed error level
#101 renamed DefaultExceptionHandlerListener
#101 MutableStatusBar: removed the border of ExceptionNotificationStatusPanel and add it here as a listener to DefaultNavigatorExceptionHandler
#101 ExceptionNotificationStatusPanel: make the panel only visible when the icon is visible
#101 ExceptionNotificationStatusPanel: renamed letIconFlashOrShowAnEmptyPanel() + javadoc
#101 moved DefaultNavigatorExceptionHandler and DefaultExceptionHandlerListener to cismet-gui-commons
Merge branch 'feature/101Exception-Notification-Status-Panel' into dev