Workaround for hex-colors in include-option

Hex-Colors didn't work for me, so I did this dirty fix. If there's a better option please tell me.

Now I can do:

```javascript
stylus: {
    compile: {
	  options: {
		define: {
           'colorone': "#E65213",
           'colortwo': "#E22E1D",
}
```

Before it results in "#E65213" in my CSS. Now the string will be unquoted.