Updated readme.txt, address-fields.php, and several other issues

Hey there, love ACF and love this add-on, nice work!

Updated several things here:

* Noticed an issue regarding the resources not getting added to options pages, so updated that (#11).

* Finally, saw the issue about adding microformats to this add-on, and personally wanted that as well for my own project. So what I've done is made the default classes be the correct microformat classes based on the address spec, and then to take it a bit further, also account for the front-end address container wrap and whether people want to use a html5 <address class="adr"> or straight html <div class="adr">. So I added an additional optional that allows people to choose which parent container to use (#6).

* Updated plugin to use plugins_url() rather than base_dir

* Noticed issue https://github.com/GCX/acf-address-field/issues/10, and updated the front-end output to all be conditional. So parent wrapper only shows if have fields with data, and inner row wrapper only shows if a row has data.

* Updated readme.txt version, description, changelog

Hope this helps, and if you don't mind, I added myself as a contributor to the plugin : )

Thanks!