Merge pull request #30 from tonto/master

Move animation from temp in saveGIF
Noticed that im.convert uses ani.options outdir, so i added dir.create(ani.options(outdir))
Merge branch 'master' of git://github.com/yihui/animation into HEAD
unnecessary file.path calls
Create outdir directory structure within  tempdir since im.convert uses this assumption
merge detached head to master branch