add test for #414
option parser: remove leading :

see #413
test against rails 4.rc2
test: fix 1.8 syntax
add support for multiple attributes per shortcut

see issue #415
add tests
readme

[ci skip]
more tests
Fixed typos
Merge pull request #417 from chip/master

Fixed typos
test against new rails 4
Merge branch 'master' of github.com:slim-template/slim
Merge remote-tracking branch 'upstream/master' into README_ja

Conflicts:
	README.md