Adding data import, grade data from Summer 2013 to Summer 2014 inclusive

Notes:

* import.php only works on data after Summer 2013, as the schema of the CSV file had changed. It should be trivial to alter the file, however, to run on files before that (199908_to_201208.csv)
* Requires PHP 5.4 to run import.php currently, due to use of short array syntax. To make backwards-compatible, replace [] with array(). That being said, since 5.3 is deprecated, future development should be PHP 5.4+