Add method to append or update FR button

I must look for a better moment to append the FastReblog button
and/or update in case of first-post change.
Remove bad semicolon
Avoid incompatible type error
I'm a badass with a bad memory, so I add this
Remove first-post-change detection and other stuff
Remove comments, fix click event, fast append.

Removing obvious comments, fix click event (number passed to jQuery), and fast appending, due to change-post-count detection.
Merge pull request #1 from makzk/dev

Fix click-event, fast appending, add post-count-change detection to do nothing without more posts.