allow backticks for strings with single quotes (#49)
allow backticks for strings with single quotes (#49)

this makes a string like

```js
const str = `this string has 'single quotes'`;
```

not error, previously you would've had to do

```js
const str = 'this string has \'single quotes\'';
```

which is ugly and i don't like it.

thoughts?
cjihrig/eslint-config-hapi,continuationlabs/eslint-config-hapi