Update jquery.readmore-readless.js

Using .closest() instead of parent() allows users to move the rmrl-read-more and rmrl-read-less spans inside the rmrl-container. I'm using this for example to append the .rmrl-read-more to the first <p class="item"> and the .rmrl-read-less to the last <p class="item">.
Merge pull request #2 from mschilder/patch-1

Update jquery.readmore-readless.js Thanks to https://github.com/mschilder