Add react-native support

[aaerofeev]

Please add react-native support, I have a problem use "when" with react-native
I resolve error with "browser" key in package.json. When set key to false then works ok

[kschzt]

Transforming modules ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓░░ 94.2% (557/574)...(node:12233) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 1056): UnableToResolveError: Unable to resolve module ../when from /Users/jak/Desktop/src/vizor2/packages/vizor-editor-core/node_modules/when/dist/browser/when.js: Directory /Users/jak/Desktop/src/vizor2/packages/

[kschzt]

it's just the paths are wrong in the dist/browser/when.js, off by one folder. changing all the '../' paths to '../../' seems to help, haven't got it all to work just yet though