[Opinionated] Add alt attribute & remove container

[kurtextrem]

I've added an alt attribute, because "Placeholder" and "Worker" as alt is not really nice.
Second thing I've done is remove the container, because if you're using <ImageWorker> as replacement for <img> it should not become a <div>.

[nitish24p]

isLoading will be an unused variable.. you can change it to the following

return .isLoading ? this.renderPlaceholder() :
  <img src={imgSrc}
      style={{ ...style }} className={imageClass} alt={alt} />

[nitish24p]

So i converted it to a div because if someone supplies a placeholder as a div and then the image loads, so we will toggle from a block element to an inline element, and that may break UI. Hence i thought of wrapping it in a block element div regardless. If one wants to make the parent an inline then you can add a containerClass prop.@manjula91

display: inline-block

[manjula-dube]

Looks Good

@nitish24p I think we can merge it :)

[nitish24p]

One comment, and eslint..

[nitish24p]

can you run npm run eslint to see the lint errors and fix those

[kurtextrem]

Fixed!

But I think it should be added to the readme, because as I said I'd expect an <img> replacement to be inline too.