Bug 983172 - Parsing jpeg header information for downsampling the image for thumbnail

- Use image_utils lib for generating the thumbnail
- Use fixed thumbnail size and update the styling
Can't comment on image assets, so asking here :) I remember we used 8-bit images earlier with no visible problems, current images are 32 bit and ~3 times larger in size. Can you please check with VD if 24/16/8 bits images acceptable?