Now current build data is shown on a status bar

A status bar is added to the GUI
Change layout constraints to get free space for new status bar
Add new method to Observers MvnBuildOutputListener
Launch Oberser event when starting a new build

Closes #2
Merge remote-tracking branch 'origin/issue2' into issue2

* origin/issue2:
Now current build data is shown on a status bar

Conflicts:
	src/main/java/org/platypus/mvnWatcher/view/MvnWatcherGui.groovy