Upgrade SimplePie to 1.3

[MitchellMcKenna]

Simple Pie 1.3 is now available: http://simplepie.org/blog/2012/07/07/one-dot-three/

We are currently using version 1.2.1, it's a modified version to work with CodeIgniter: https://github.com/ericbae/SimplePie_CodeIgniter/blob/master/Simplepie.php

Need to look at what had to be changed to work in CI. It would be nice if we didn't have to make those changes for upgrade purposes.

A single file version is available like what we use now, however if we can use it without modifying it, explore installing multi-file version via Sparks or Composer (contingent on Issue #30) for maintainablity.