Polish PHP Application

I have an existing PHP application that enables users to manage their various Wordpress installs remotely. ? This includes many details of the day to day management of blogs. The software is working but could use some polish. I would like to work with someone who can do smoking hot interfaces, familiar with ajax, clean and usable design. I want to make sure that the existing php software has good error handling, can interface with a bug tracker (lighthouseapp). ? You need to be able to work well with an existing codebase, as well as work with Github.