Add Php 5.6 support
Add documentation in reStructuredText format
Add requirements file for RTD theme
Add updating documentation
Shorten the README to match

No need to have two sets of documentation any more!
Merge pull request #110 from Chassis/php-5.6

Add support for PHP 5.6
Merge branch 'master' into pin-packages
Make best-effort attempt to match version

As it turns out, this likely won't work, but we'll try anyway. APT
packages "expire" once new ones are released, so using a specific PHP
version here is likely to break.

We'll handle this some other time, but for now, let's do our best at
setting the policy.