Leave default ruleset

I want the same as CSSLint and jsHint, the handling of the default rule set.

```js
{
    'doctype-html5': true
}
```
is as follows.
```js
{
    'tag-pair': true
    'tagname-lowercase': true,
    'attr-lowercase': true,
    'attr-value-double-quotes': true,
    'doctype-first': true,
    'tag-pair': true,
    'spec-char-escape': true,
    'id-unique': true,
    'doctype-html5': true
}
```


Set to false, defalut rule disabled.
```js
{
    'tag-pair': false
}
```