Fixed incorrect slicing when slice is 0 or null

[electerious]

It's currently not possibly to save a path with the value 0 or null because the if returns false when obj[key] is 0 or null. Caused me a lot of headache.

I saw you're already working on v1.0, but I hope you're releasing this a bugfix for the current version. It's causing a lot of trouble in my application.

Thanks!

[johndturn]

@elgerlambert Any idea on when this should be fixed and pushed out? Until that point, this is a blocker for me to use this in my application. Otherwise, it works really well!

[giannif]

@jdt1204 you can use a custom slicer passed to persistState in the meantime

const slicer = paths => state => {
    const subset = {}
    paths.forEach(path => {
        // default implementation does a falsy check on state[path],
        // which means false doesn't save hrmph
        subset[path] = state[path]
    })
    return subset
}

compose(applyMiddleware(...middleware), persistState(localStorageProps, { slicer }), devTools)