Conditional spriting based on image url

[linxiaowu66]

Add an option to conditionally filter images based on the image URL

For example, any image with ?__spriter will be sprited

background-image: url('./images/test.png?__spriter');

[MadLittleMods]

Just in case you weren't aware and for people who stumble onto this issue. You can already conditionally render images with comments with some meta info in them, see https://github.com/MadLittleMods/gulp-css-spriter#meta-info

[MadLittleMods]

@xing-zhi We should make this a more general option for a matching function or regex, options.filter(uri, filePath)

#11

[linxiaowu66]

@MadLittleMods Thanks a lot.