Use exec to run phpdoc so phing can use the phar files
Adds comment for nginx

This Commit adds informations on what to do to get the API up and
running on an nginx-server. This might also work for all other ways than
an apache-httpd
Merge branch 'EricHogue-RunPhingTaskFromPharFiles'
tidying up the readme
Merge branch 'heiglandreas-feature/DocumentNginxTweaks'