Increase version number to 0.1.0 for first release
Capture and log ImageOptims verbose output

Set verbose option to true by default.
Return source file if ImageOptim does not return an optimized one

ImageOptim returns nil on successful runs if the output file is
not smaller than the input. We cannot treat that as a failure and
therefor return the unoptimized image.
Increase version to 0.2.0