made some changes to responsive image tasks, and options, better directory structure, better sizes, nameing convention etc, also included more clean task subtasks to remove responsive generated files
changed path of responsive images to indicate temporary nature, since I dont plan on commiting them
added an image w/ responsive image name pattern, grunt will automatically resize it for use with picture elemnt etc
added responsive-tmp to ignore, dont wanna commit these outside of the build itself, the source images are already added elsewhere
added srcset attribute to front page image, uses responsive images generated by grunt-responsive-images, need to add focal point art direction thing, sizes for small, medium and large, see #1