Fix use of tmp_name; add parameters for jpgQuality

I didn't understand the two parameters (name, tmp_name) passed to several of the image modification functions. The uploaded image won't be at both locations, but both locations were use. These changes cause several functions to only use the tmp_name parameter, leaving the name parameter unused.

Also, when doing a resize, always saving to jpg 100 quality caused some uploads to radically increase in size. This ought to be user-defined behavior (with a reasonable default), so my purposes I went with 75 and made it a class member variable that can be changed in the future.