add PHP implementation

[mapsam]

Should add an example directory for a PHP (server side) implementation of this library since we use it on WordPress frequently enough. Doesn't need to be config heavy, but could take in some general parameters to build accordingly. Essentially, this would really only need to be a CURL call and a config file to set up for a cron job situation instead of calling the API via javascript. Then the instagram-grid.js will run accordingly, making the ajax() call to a local.

Files needed:

1. config.php for setting up the library and instagram calls with API credentials
2. loop.php would build the data and set in a local directory
3. build in a parameter for instagram-grid.js that sets the local path to file instead of calling the instagram library (assuming your PHP has built the json appropriately. Should build the rest accordingly since the json specification will match.