move initializer in separate module

as discussed in #38 with the following it should be possible to use `ember-load-initializers` to load the emberui initializer without requiring it automatically

in other words

if you use `ember-cli`

it's currently possible to use the named-amd build of emberui with ember-cli

it's as simple as 

```
app.import('vendor/emberui/dist/named-amd/main.js', {  
  'emberui': ['default']                                         
});                                                                                                                                                                                                
app.import('vendor/emberui/dist/emberui.css');                                                                                                                                                         
app.import('vendor/emberui/dist/default-theme.css');  
```

but in order for the initalizer to trigger you then have to
```
loadInitializers(App, 'emberui');
```

the `main.js` build still loads the initializers instead so that the behaviour if you require the default module or use the `global` build it's maintained

/cc @jdjkelly @tonywok @elucid