LocalStore.js now accepts false, 0 etc. in defaultVal 

It was impossible to set `defaultVal` to `false` or `0` when creating new `LocalStore` item:
```js
// Before
var loggedIn = new LocalStore('loggedIn', {defaultVal: false})
console.log(loggedIn.get()) // null

//After
var loggedIn = new LocalStore('loggedIn', {defaultVal: false})
console.log(loggedIn.get()) // false