Use render control image format.
Improve control image format feature.
Remove redundant lower().
Comment why need doing something specific with 'bmp'.
Catch PIL/Pillow IOError.
Refactor utils.image_mimetype
Refactor utils.parse_render
Fix render argument didn't work bug.
Limit available image formats.
Fix "IOError: cannot write mode RGBA as XBM."
Change mime type of bmp image to "image/bmp"
Adjust exceptions handling
PEP8 tidy
Merge pull request #18 from mozillazg/feature-render

Use render control image format