[Shotwell] [future request] add some default verbosity

[Alexey Fisher]

Hallo devs,

i have some crashes with shotwell 0.8. It happens on import or on
library update. At the same time i get "Error: Directory NikonPreview
with 21313 entries considered invalid; not read." After some googling i
found this mail: http://osdir.com/ml/digikam-users/2010-08/msg00086.html
it says, this message come from lib exif2.

I still can't find if this error is the reason of the crash. Some times
i get many of this errors and shotwell is working, some times it crashes
after few of them.

My [future request] is to add some default verbosity. For example on
photo import shotwell should write to terminal the path of current
photo. So if it crashes i can find where it was.
Second: is to fix this message "Error: Directory NikonPreview with 21313
entries considered invalid; not read." it says almost nothing. It should
be some thing like this: 
shotwell: read image, path: /home/bla/Bilder/someimage.jpg
libexiv2: can't parse exif of image: someimage.jpg
libexiv2: 'NikonPreview' entry is too big (21313 byte). Skip it.

-- 
Regards,
        Alexey