Webpack 2 support

[s-bilous]

Method require.ensure in webpack 2.1.0-beta.25 now return a Promise, so with this loader i get exception: Uncaught TypeError: Cannot read property 'catch' of undefined

[NekR]

@s-belous yeah, I can do that. Thanks for reporting this :-)

[nickcmaynard]

I just upgraded jsonschemalint.com to Webpack 2, and had to rip out async-module-loader because of this :( Definitely a +1 from me.