cropping by Imager
tests
use Imager for convert()
Merge remote-tracking branch 'origin/master' into gfx/imager
add tmp/
query_cache on
update nginx.conf
image quality: 90 (default to 75)
Merge branch 'gfx/imager'
Merge branch 'master' into convert_cache

Conflicts:
	perl/lib/Isucon3Final/Web.pm