Fix issue #7 and directory structure

As a PHP developer and avid vim user, I was very disappointed by the general lack of PHP support for vim. I was pleased when I found php completion for vim, but dismayed when I learned that it was, apparently, undeveloped for a while. In the hopes that this can be resolved, I have fixed the directory structure and a rather annoying bug (fix taken from here: https://groups.google.com/forum/?fromgroups=#!topic/vim_dev/x8_OQRWpUZE), and hope to refine the plugin further in the future.

I would like to see true namespace support added and the current hackish method of generating a new window as part of the completion function refactored, and am more than willing to give it a shot myself. For now, I hope these changes will be useful to other PHP developers.