Merge pull request #14 from lidaobing/master

support asset-url
Merge pull request #16 from rdd-giga/master

use montage to generate the css sprite
do not restrict ruby version in .rvmrc
fix mocha require warning
add "-gravity West" option
option geometry should be +0+0, otherwise image position y is not correct
Bumping version to 2.0.0
change default path to app/assets/images and app/assets/stylesheets
set default engine to css.scss
set default css_image_path to assets
do not do optimize by default
update README
add use asset-url section to README
add config css_images_path_relative for example
add example
add exmaple to README
Bumping version to 2.1.0
use RbConfig instead of Config
remove .rvmrc
Merge remote-tracking branch 'upstream/master'

Conflicts:
	.rvmrc