Support prepend and append props

[frux]

<SimpleTable
    ...
    // prepends cell with some data in the begining of each row
    prepend={item => (<span>{getSomeData(item.id)}</span>)}

    // appends cell with some data to the end of each row
    append={item => (<span>{getSomeMoreData(item.id)}</span>)}
    ...
    />