Tumblr button type

[mikwee]

It may not be as big as it once was, but Tumblr still has a relatively big userbase, standing as the world's 119th most popular site, According to Alexa. I think it deserves its own button type.

[pierreericgarcia]

Hey @mikwee I've just made a PR that solves this issue, now waiting for @rcaferati for reviewing :)

[mikwee]

Thx! I actually replaced this library with React Bootstrap due to the staleness, but I'm glad to know the project still has its passionate devs, and maybe I could use it in the future!