Add support for atlaskit with server-side rendering

Basic approach

• Left ACE itself untouched

• Wrote a custom express template engine that dynamically requires the transpiled version of the jsx, server-side renders it and populates a handlebars template with the html and the necessary script for rehydration. Added a parameter to do browser-only in case there are issues with the SSR.

• Added explanatory comments and updated the example views to include some jsx.

• Updated the start script; added build and watch scripts.

Result

Next steps

• Update ace docs (and maybe tweak ace code if appropriate)