Fixed bob bio dir x_labels and y_labels

The labels of the DIR plot were incorrect.

This is the fix.

I will merge this if you don't mind @theophile.gentilhomme and @amohammadi

bob/bio/base/script/figure.py

@@ -76,8 +76,8 @@ class Dir(measure_figure.PlotBase):
         self._semilogx = ctx.meta.get('semilogx', True)
         self._rank = ctx.meta.get('rank', 1)
         self._title = self._title or 'DIR curve'
-        self._x_label = self._title or 'FAR'
-        self._y_label = self._title or 'DIR'
+        self._x_label = self._x_label or 'False Alarm Rate'
+        self._y_label = self._y_label or 'Detection and Identification Rate'
 
     def compute(self, idx, input_scores, input_names):
         ''' Plot DIR for dev and eval data using