Fix crashes occurring after deleting a buffer.
The issue was that deleted buffers were still left being displayed in the interface, so any attempt to delete a buffer was causing app crashing.  This switches the displayed buffer to an empty buffer upon deleting a buffer, which prevents the crashes.
Merge branch 'bufferdeletebugfix'

Conflicts:
	QuasselDroid/src/main/java/com/iskrembilen/quasseldroid/service/CoreConnService.java