[RFC] Convert source module format from ES6 to CommonJS

The [es6 module transpiler](https://github.com/square/es6-module-transpiler) currently doesn't have a way to exclude 3rd party libs (and even if was added the grunt plugin is out of date anyway) which meant we have had to keep copies of React lib files converted to use es6 module imports in our repo, this is bad practice as it means we are unnecessarily locking react bootstrap to a specific react version and with React 0.11 on the near horizon not having this could make the transition between React version difficult as we can only support one version at a time. This change swaps the module format to CommonJS which (for the moment) has more mature tooling support allowing this functionality.

When swapping out the import statements i removed the additional whitespace aligning the `=`'s, this was becoming difficult to maintain and i didn't think worth the work to keep them in sync.

The tests are all passing but are throwing up the following error:
```
WARN: 'Warning: You are calling cloneWithProps() on a child with a ref. This is dangerous because you're creating a new child which will not be added as a ref to its parent.'
````
Since i haven't changed any functionality i assume we had just removed this error in our version of `react/lib/cloneWithProps`? But guess we will need to fix this properly if this change goes through.

The AMD files will need additional testing, i am just wrapping the CommonJS modules with `define(function (require, exports, module) {});` via [grunt-amd-wrap](https://github.com/domenic/grunt-amd-wrap) and it looks like it should run fine to me but i don't have a proper AMD project to test it in.

@stevoland how do you feel about this? I know we have only recently switched to es6 modules and it would be nice to transition back once the tools have stabilised.