adding changelog

Signed-off-by: Bravocado <bravocado.project@gmail.com>
update readme. fix Compass compatilibity issue (mixin background-image)

Signed-off-by: Bravocado <bravocado.project@gmail.com>
removing add-prefix function

Signed-off-by: Bravocado <bravocado.project@gmail.com>