Added js build for webpack compatibilty

[vegetableman]

Ran in to the jsx issue when doing a require using webpack:-

ERROR in ./~/react-tabs-component/Tabs.js
Module parse failed: /Users/viven/Projects/dummy/node_modules/react-tabs-component/Tabs.js Line 62: Unexpected token <
You may need an appropriate loader to handle this file type.
|                       var isActive= tabNum===this.state.activeTabNum;
|                       return (
|                               <span
|                                       key={'tab-'+tabNum}
|                                       className={isActive? activeTabClassName : tabClassName }

The build task splits out a regular js file for easier sharing.