Update React version

Hi, the main issue with developing anything for `hexo-admin` is the fact that the version is sooooo low. As a beginner with react I am going to update react to at least [^15.6](https://github.com/facebook/react/releases/tag/v15.6.1) in my fork.
What do you think about the idea? Do you have any practical advices?
Also I am thinking about bundler - now hexo-admin uses `gulp` + `browserify`, but what about `webpack` which I see as "more natural" for react ecosystem?

The issue names no files or tests. Start by inspecting the current React dependency and the gulp/browserify build setup, then evaluate the proposed React 15.6.1 update and webpack migration against the repository. Done requires a maintainer-approved scope and verified implementation, but the issue does not define either.

Written by the indexing model from the issue text.