Added two filters before and after the panel content output

Hi Greg!

We needed an inner-wrapper area just after outputting the `.panel-row-style` for display purposes, this is an extension to the work from Primoz (http://siteorigin.com/thread/pull-request/).

We've found that this is fairly common with Foundation 5 (http://foundation.zurb.com/forum/posts/3097-full-width-row-with-grid-row-content) in order to create full width **rows** with centered content and this solves the problem of needing additional markup in the rendered panels output.

Really enjoying the plugin!