Implement juju generate-config

Replace incorrect 'generate' with 'generate-config' as an alias to init.
Add support for multiple edit commands
Always show hints
Merge pull request #23 from marcoceppi/edit-cmds

Add support for multiple edit commands
Merge pull request #24 from marcoceppi/show-hints

Always show hints
Match 'generate-config' as a valid lesson check
Adding 04-service-configuration lesson.
Merge pull request #22 from kwmonroe/generate-config

Implement juju generate-config
Adding lesson to the array of lessons.
Merge pull request #26 from mbruzek/service-configuration

Service configuration