move 'react-syntax-highlighter' to devDependencies

[mikaello]

Using command: npm install [email protected] --save-dev

Sorry for the mess in #33, I'll keep this branch clean :-)

(and if you're interested in any of the features I have implemented in my own fork (http://github.com/mikaello/modali), I'll be more than happy to prepare PR-s for those of interest).

Resolving issue #28

[jcrowson]

Fantastic, @mikaello ! I'll merge this in now.

[dinoshauer]

@jcrowson gentle bump :) I guess this would fix the security warning for highlight.js