Remove style attributes in favor of CSS class

[blakestone95]

A team member switched us to this library from material-design-icons, but it messed up a bunch of our styling. After perusing the source code, I have a suggestion: remove the style attributes used in Icon and SvgIcon and instead use a CSS class (perhaps className="react-icons-kit") with some CSS to apply the inline-block and vertical-align rules. My reasoning is that this will make it easier to style the icons and override your defaults without having to add a className and style to every Icon component.

[wmira]

@blakestone95 apologies for the very late reply. I will update this such that users should be able to compose a specific container of their liking -- e.g. with their own default className. styles will also be not added by default. Will update once it gets released