remove unneeded step of copying jQuery in paver builds

We've been copying `jquery-1.10.2.min.js` to `jquery.js` at the end of every paver build to override the really outdated version of jquery that Sphinx includes automatically. However, I just realized that files copied from `common` to the static output directory will override any files that Sphinx includes (this is by design; there's a comment to that effect in autogenerated `conf.py` files.

So, if we rename `common/jquery-1.10.2.min.js` to `common/jquery.js`, it will automatically override the old version of jquery. 

This rename will also simplify the process of creating a new book.