This method goes down to `MagickGetImagesBlob`, which allows for
creating animated gifs.
I didn't abstract out common operations between the two in the interest
of not overly polluting the codebase. However, this new method is almost
identical to `write_image_blob` so you could probably abstract something
out of there.
Leave the generated bindings out of the source repository and instead
have Cargo automatically build them if they are missing. This allows the
version of MagickWand to be incorporated into the bindings
automatically. For instance, in Homebrew the version is 6.Q16, while on
FreeBSD 10.2 it is 6.9, and only be generating the bindings for each
system can we ensure a smooth compilation process.
