initial support for packaging for chrome/android/ios

Using https://github.com/MobileChromeApps/mobile-chrome-apps to convert the chrome app into a cordova app. This (in theory) gives us the potential to code to the Chrome App API and have that API translate over to Cordova for us. The status of the API can be found here:

- https://github.com/MobileChromeApps/mobile-chrome-apps/blob/master/docs/APIStatus.md

A blog post introducing this approach of "mobilizing chrome apps" can be found here:

- http://blog.chromium.org/2014/01/run-chrome-apps-on-mobile-using-apache.html

See README.md for more details.
moved cordova out of build

`gulp-cordova` now copies `build/chrome` to `cordova/www`
cordova should symlink to the chrome app

See: https://github.com/MobileChromeApps/mobile-chrome-apps/blob/master/docs/CreateProject.md#step-2-create-a-project
bump React
build cordova platforms on demand

This allows us to keep cordova/platforms out of src control. This also allows us to perform a full and unambiguous clean of the cordova projects.
merge react bump from master
Build for Web/Chrome/iOS/Android

After merging this branch you should be able to run:

- `npm i`
- gulp ios --emulator`

..to run the app in an iOS emulator. Still TODO:

- dist-chrome: Package chrome app as .crx file
- dist-ios: Package ios app as .ipa file
- dist-android: sign and version the .apk
favor `chrome:build` over `build-chrome`
added support for packaging a chrome .crx file
favor `run:ios` over `ios:run`
update README
remove extraneous logging and organize gulpfile
android packaging
alias build:[android/ios] to build:cordova
fixed cordova/www -> build/chrome symlink
build-cordova -> build:cordova
merge master
travis badge on README