Bug fixes and improvements

Had a number of problems when installing this plugin and I thought I would fix them. The biggest ones were that I wanted to proxy the curl request. So I replaced it with the built in WordPress wp_get_remote function. I was also unable to see the panel in the admin, which I have also fixed. 

Here is a full list of changes. 

* Removed references to CURL and replaces with the built-in wp_get_remote function.
* Fixed bug where admin panel was no accessible by admin accounts.
* New filter 'disqus_rcw_recent_comment_format' for change the html markup of each comment