feat(Gruntfile): Adds imagemin task and image watchers
feat(Gruntfile): Adds responsive_images task, commented out temporarily
feat(Gruntfile): Adds s3 deployment task
chore(Gruntfile): Tidies up file
fix(Gruntfile): Removes reference to *secret* AWS credentials json file to fix build :+1:
fix(Gruntfile): Removes reference to S3 task temporarily :+1: