Allow 4096bit keys to be generated, and replace (most) short tags.

1. A simple bug was preventing 4096bit keys from being generated - fixed in commit 4295bd6.
2. Replaced a number of the php short tags, as phpki was erroring out on CentOS 6.4.
3. Updated some of the code to be HTML5 compliant.

This is tested working on CentOS 6.4 with php 5.3.3