Fixed camera settings

Since splitting the camera config into a separate YAML file, we've broken
the ability to change the camera's configuration via the API (or at any time
except when the camera is set up, I think).  This (mostly) fixes that, though
I get type errors that I've had to work around (e.g. when setting
shutter_speed), see `pi.py`

openflexure_microscope/microscope.py

@@ -192,7 +192,7 @@ class Microscope(object):
         # If attached to a camera
         if self.camera:
             # Update camera config
-            self.camera.config.update(config)
+            self.camera.apply_config(config)
 
         # If attached to a stage
         # TODO: Convert stage settings into a config expansion