fix #164 content not shown until clicked with initOnClick set to true

[FWennerdahl]

This doesn't work as intended. The undo module isn't loaded when the "initializationDelayed" event is fired, causing the call to "undo.reset" on line 77 to throw an error. We'll take another look at this and update.

[FWennerdahl]

Updated $render to delay resetting the undo history until the editor is fully initialized when using initOnClick.

[stefanneculai]

Fixed in https://github.com/froala/angular-froala/commit/01bcc7d669eb2e9dc8f1ea2142ce671604762d4b.