[Proposing new feature] zeplin pull

[vitorcamachoo]

Hi, when this latest version was released, I tough it had some tool to update projects with the styleguide present on Zeplin. My suggestion is to create a new command called pull which does:

• Based on the configuration (.zeplin/components.json) and some reference for the wanted plugin (example: styled-components), generate the styleguide theme object with all the configuration, example:

// generated styleguide
export default {
    colors: {
        primary: '#cccccc',
        'primary-light': '#cccccd',
        white: "#ffffff"
    },
    typography: {
        h1: {
            'font-family': 'SFUIText',
            'font-size': '16px',
            'font-weight': 'bold',
            color: '#000000',
        }
    },
    components: {
       // this is based on the selected extension to transform in a desired way
        Button:  theme => ({ 
            color: theme.color.white,
        }),
        H1: theme => ({
            ...theme.typography.h1,
        })
    }
}

So, the idea behind this, is every time I execute zeplin pull, it generates the theme object for a destination path and it updates our projecto dynamically, syncing all the designers modifications with the source code.