Added .gitignore
Now uses default image quality instead of requesting optimizeQuality

Firefox reportedly gives better quality using 'auto' (its default)
than with optimizeQuality.  I don't see any difference on OS X but
perhaps this will help on Windows.  At issue is mainly interpolation
when down-rezing an image.

Suggested by 'tophf' on TZP's wordpress site.
Fixed 500px.com per site changes