v0.0.8

1. Image metadata (PNG only) - #165 (@joannajw)
2. Node 4 support (Upgrade to NAN 2) - #182 (@kant2002, @weareu)
3. Update CImg (6fee35d), giflib (8bd1b91) and libpng (a2791c9).
4. Fix bug caused by raw pixels buffers with other than 4 channels (1138482).

Many thanks to @antoinepairet and @unbornchikken for their help with #182.