Custom CKEditor plugin button not showing - ckeditor

Question

Feel like I should have been able to track this one down already. I need to create a custom plugin for CKEditor (I'm using 4.3.1). To get started I used the guide found here (http://docs.ckeditor.com/#!/guide/plugin_sdk_sample_1). I downloaded the code and put it in my ckeditor\plugins folder. So, now I have ckeditor\plugins\abbr. I'm not sure what I'm doing, but the button is not showing in the toolbar. The code is below. My questions are, where should I define the "abbr" extra plugin? Do I do it in my _Edit.cshtml page where I'm defining stylesheetparser? Or put it in config.js? Given the setup below shouldn't the button show up next to the source button? Do I need to include it in config.js or does the plugin code take care of that?
Been doing a little playing around and it does show up if I use the full toolbar, but not when I customize it.
config.js
CKEDITOR.editorConfig = function (config) {
config.toolbar = 'MyToolbar';
config.forcePasteAsPlainText = true;
//config.extraPlugins = 'abbr';
config.ignoreEmptyParagraph = 'true'
config.toolbar_MyToolbar =
[
{ name: 'document', items: ['Preview', 'Print'] },
{ name: 'clipboard', items: ['Cut', 'Copy', 'PasteText', '-', 'Undo', 'Redo'] },
{ name: 'editing', items: ['Find', 'Replace', '-', 'SelectAll', '-', 'SpellChecker', 'Scayt'] },
{ name: 'basicstyles', items : [ 'Bold','Italic','Subscript','Superscript','-','RemoveFormat' ] },
'/',
{ name: 'insert', items: ['Table', 'SpecialChar'] },
{ name: 'styles', items : [ 'Styles'] }
, { name: 'source', items: ['Source', '-', 'abbr'] }
];
};
_Edit.cshtml
#Html.TextAreaFor(e => e.Narrative, 10, 10, null)
<script type="text/javascript">
CKEDITOR.replace('Narrative', {
extraPlugins: 'stylesheetparser,abbr',
// Stylesheet for the contents.
contentsCss: '#Href("~/content/"+#Model.CssFile)',
stylesheetParser_skipSelectors: '',
disableNativeSpellChecker: false,
// Do not load the default Styles configuration.
stylesSet: [],
height: '600px',
width: '100%'
});
</script>
plugin.js
CKEDITOR.plugins.add( 'abbr', {
// Register the icons.
icons: 'abbr',
// The plugin initialization logic goes inside this method.
init: function( editor ) {
// Define an editor command that opens our dialog.
editor.addCommand( 'abbr', new CKEDITOR.dialogCommand( 'abbrDialog' ) );
// Create a toolbar button that executes the above command.
editor.ui.addButton( 'Abbr', {
// The text part of the button (if available) and tooptip.
label: 'Insert Abbreviation',
// The command to execute on click.
command: 'abbr',
// The button placement in the toolbar (toolbar group name).
toolbar: 'source'
});
// Register our dialog file. this.path is the plugin folder path.
CKEDITOR.dialog.add( 'abbrDialog', this.path + 'dialogs/abbr.js' );
}
});