Added YIFullScreenScroll 1.0.0

Thanks for merging previous `YIDragScrollBar` to master repo :)
This is my 2nd library to submit. Spec-lint is done right.

By the way, there are still several libraries that I want to share and fix.
Should I keep sending pull request for each one, or can't I just have push access to master repo?
Please let me hear about current CocoaPods community's push policy.

Thanks.