Remove unnecessary `when` clause for OmniOS and SmartOS
Use alpha ordering to sort version manipulation tests
Add Raspbian and Pidora to platform truncator. Fixes #349

These are Raspberry Pi variants of Debian and Fedora.
openSUSE/SLES fixes for OHAI-339

Ohai 7 introduced some changes to the platform returned on openSUSE and
SLES systems. This change standardizes on identifying openSUSE as 
`opensuse` and SLES as `sles`.