Don't let HTML-like filenames be interpreted as HTML strings

So that filenames that look like HTML don't get fancy-formatted when
we show info about them (i.e. on hover)

This patch fixes the same issue in two places:
 - dolphin, by setting Qt::PlainText on the status bar's label
 - konqueror, by escaping setStatusBarText strings emitted by
   DolphinPart

BUG: 321778
FIXED-IN: 4.11.0
REVIEW: 111746