Add Jest test framework

[gios]

Please, add support of Jest. It's more compatible with React.

[newtriks]

@gios thanks for the comment, could you list the compatibility advantages over the current setup? Hacks like this still turn me off for using with Webpack: http://stackoverflow.com/questions/28870296/how-to-use-jest-with-webpack. If you wanna add as an additional option and send a pull request that would be appreciated > #27.