fix ruby package logic for trusty,
Added warnings if a ruby version specified isn't going to be found without adding a package repository.
Can now set the system default ruby binary. Tricky as support for ruby has been dropped from update-alternatives in 14.04... may or may not come back...
depreciate the switch parameter, and change the rubygems update to use notify rather than subscribe.
Add support for the Debian rubygems-integration package
Reorganising and completing the tests for the base class including tests for the Amazon distro (a cut-paste of RedHat)
Update documentation and use notify, rather than subscribe
...that's what the tests want.