Database reset

[fmalcher]

• additional table for settings (?) as key/value store (maybe we can use it for something else later, so keep it generic)
• Flag resettable = true
• REST endpoint /reset that resets the DB with sample values

[fmalcher]

I'd rather like to see a more "speaking" word here than devMode.

1.) Imagine, the dev mode enables some more dev features – we can't disable the database reset then because it's hidden in the devMode feature.

2.) devMode does not explicitly claim that a database reset is actually allowed – it could mean anything from performance stuff over debugging features up to missing build optimization. A more specific verb would be less ambiguous here. I suggest resettable or databaseResetAllowed.

@rweisse

[rweisse]

See #35