If I only had a brain...

Inspired by http://www.reddit.com/r/feedthebeast/comments/1cuxxl/dear_modders_please_please_please_add_something/

I've seen a few calls now for something to repel mobs. 

We already have a scarecrow- nobody seems to use it, probably because it doesn't really do anything.

Here's a change that causes creepers to flee when scarecrows turn to face them.

Basically, uses the same behavior that cats trigger, but should have +50% range.

And we can easily make additional mobs/animals get scared by Mr. Scarecrow in the future.