Silex

This branch adds the silex REST API framework, and implementations of all the defined endpoints using that.

The database handling has been switched from old mysql_* functions to object-oriented MySQLi.

There are a couple of database changes too; the requests table and results table have been added

The tempURLs table is now uniquely indexed so that a target URL only appears once.  Where multiple users have requested the same URL, each of the requestors is associated with the requested URL.

The API is now able to serve up test URLs and record results.