refactors focal length episoln out of base

ale/drivers/base.py

@@ -520,10 +520,6 @@ class PDS3():
     def _target_id(self):
         return spice.bodn2c(self.label['TARGET_NAME'])
 
-    @property
-    def focal_epsilon(self):
-        return float(spice.gdpool('INS{}_FL_UNCERTAINTY'.format(self.ikid), 0, 1)[0])
-
     @property
     def starting_ephemeris_time(self):
         if not hasattr(self, '_starting_ephemeris_time'):
@@ -582,6 +578,7 @@ class Spice():
         Called when the context is created. This is used
         to get the kernels furnished.
         """
+        print(self.metakernel)
         if self.metakernel:
             spice.furnsh(self.metakernel)
         return self

ale/drivers/mdis_driver.py

@@ -65,6 +65,10 @@ class MdisSpice(Driver, Spice, Framer):
         # eval at the focal_plane_tempature
         return f_t(self._focal_plane_tempature)
 
+    @property
+    def focal_epsilon(self):
+        return float(spice.gdpool('INS{}_FL_UNCERTAINTY'.format(self.ikid), 0, 1)[0])
+
     @property
     def starting_detector_sample(self):
         """