Fix build on Ruby 1.8.7
Add Linux support

This provider uses Kernel::at_exit instead of a separate watcher
process. This technique should be portable to the Windows provider as
well. Note that rebooting will silently fail if the user Puppet is
running as lacks permission to run the shutdown command.
Refactor prompting into a feature

Windows is the only system that supports reboot prompting, so it makes
sense to make this a feature rather than a requirement of the type.
Add Linux acceptance tests and nodesets
Cleanup test setup and beaker-*.cfg
Merge pull request #1 from cyberious/elyscape-linux_support

Cleanup test setup and beaker-*.cfg
Update metadata.json
Merge pull request #57 from elyscape/linux_support

Add Linux support