Fix #65: Provide optional argument for install to skip DB installation

[Dagefoerde]

This adds the option to pass --skip-db-install to the install command, causing the InstallerFactory to omit core/plugin installation.

Sorry, I have no idea on how to test this properly, given that I'd need to test the absence of an installed DB... If you have any idea, feel free to suggest / add to this branch.

Either way, the existing workflow is not broken, as confirmed by your existing tests.

Cheers!

[polothy]

Thanks! Ended up renaming the option to --no-init

[polothy]

If you want to try it out, you can use: - composer create-project -n --no-dev --prefer-dist moodlerooms/moodle-plugin-ci ci dev-master but remember to switch it back later.

[Dagefoerde]

@mrmark thanks for the hint, will try next time! :)
(Also, many thanks for incorporating this! This should speed up our initial stage.)