Ability to add Style for AlertLists

[KimberlyYang]

Hi! First of thanks for a great Library.

My query is about adding extra styles for the "Type" of alerts in the AlertList component
With the new Bootstrap 4 We have 3 extra types ..

• Secondary,
• Light,
• Dark

The current Implementation Limits the AlertList types to

• Success
• Warning
• Danger
• Info

if a style property was added to the type this could be remedied and would allow for Expansion of the layout types in a Generic way..

I can se that react-jss is already a dependency for "Themed Alert" that could be used in the List as a style parameter..
or if that is to much could we allow the component className to parse through from unknown type instead of undefined this would at leaste allow for css stryling?

[chadly]

We implement it using jss so that the styles can be overridden. To fix your issue, we would need to add secondary, light, & dark to styles.js.

I'd be happy to review a PR.