bump gulp-compass version.

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>
update readme

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>
update travis config.

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>
Merge pull request #24 from appleboy/patch

bump gulp-compass version.