Example usage

options:

1. -k: api keys, seperated by ,
2. -c: thread pool size
3. -i: input path
4. -o: output path
5. -C: write target image to yyyy/mm subfolder, the date uses image capture date
6. -K: copy the file to output path if compress failed anyhow

> java -jar picc-1.2-SNAPSHOT.jar -i ~/pics/ -o ~/compressed/ -k key1,key2 -c 20 -C true
done! 12 MB => 4 MB