cljr-move-to-let

@magnars This isn't finished yet, but I thought I'd add it here in case you were interested in it.  It seems to work when I eval it in Emacs, but the test fails.

Also, I'm sure there are edge cases where it behaves interestingly... for example if the surrounding let is (let [] ...) then you get a blank line above your added let binding.  Also, if there is no surrounding let binding it should probably tell you so, and just fail.

I'm pretty new to elisp, so any suggestions for improvement are welcome.