Support new 1.9 hash syntax

[a2ikm]

Hi,

This change enables to support new Ruby 1.9 style hash syntax like below:

Haml:

%a{title: 1 + 1, href: "/#{test_obj.method}", height: "50px", width: "50px"}

will be converted to Slim:

a title=(1 + 1) href="/#{test_obj.method}" height="50px" width="50px"

Thanks!

[mpelzsherman]

Please consider merging this, thanks.

[MichaelSp]

+1

[fukajun]

+1

[minad]

@fredwu ping, happy 2016 btw :fireworks:

[brand-it]

+1