Updated bannerify() function

1. Function no longer runs on carousels with only one banner, as it's
pointless to do so.
2. When switching banners, the function first checks whether it has
added any banner page buttons prior (as according to the `addPageBtns`
boolean), then only it proceeds based on that. This is to prevent an
undefined error from occuring.
Updated bannerify() function
Fix detached head
Merge branch 'master' of https://github.com/Zeneraith/Zenplate

Conflicts:
	js/plugins.js
Fix detached head