Blendm3 is a Blender plugin to work with StarCraft 2's m3 files being developed by Alexander Stante. While animation and exporting aren't yet supported, they are already in their development goals.
From Stante's comment on Blendm3's asset page:
Animation is currently not supported, but will be the next big goal. In a first step I plan to correctly support the importing of bones. About export, I think it you have to wait till the functionality is implemented. As I said, feedback especially if something does not import correctly, is very welcome.