Add prefrenceFragment

But keep PreferenceActivity for retro compatibility.

Signed-off-by: Sébastien MICHEL <michoux@gmail.com>
Add mimeFilter to take into account only jpg

known issue: Dispite of this filter some apps (Like ES explorer) propose
Photocaption to open non jpg images. I have to enhance robustness for
that.

Signed-off-by: Sébastien MICHEL <michoux@gmail.com>
Robustness

Robustness when trying to open file that doesn't exist on mediastore.
Next step: try to open it without Adapter handling.

Signed-off-by: Sébastien MICHEL <michoux@gmail.com>