Add request uri validation for static files

Without this validation you can get any file the webserver has read access to, major security risk, but an easy fix.

The test:

```
<?php
$fh = fsockopen('localhost', 8080);

fwrite($fh, "GET /../src/main/java/io/torch/Server.java HTTP/1.1\r\n");
fwrite($fh, "Host: localhost\r\n");
fwrite($fh, "\r\n");

while(($line = fgets($fh)) !== false) {
	echo $line . PHP_EOL;
}
?>
```

Before: Returns the source of 'Server.java', After: Returns 404