Spring Add MediaType.TEXT_CSS

Add new MediaType "text/css" and TEXT_CSS_VALUE constant to more easily define a CSS resource in spring web. Text/CSS is a standard MIME_Type and MediaType

Comment From: rstoyanchev

Thanks for the suggestion, but we don't aim to expose all standard MIME types as constants via MediaType. You can create your own constant.

Comment From: IAmLuisJ

I agree it wouldn't make sense to cover all MIME Types but text/css has to be a pretty popular one for spring web wouldn't it? It currently supports text/html.

I appreciate you reviewing the suggestion!