[WIP] orm provider and content repository

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | TODO
| Fixed tickets | #95
| License       | MIT
| Doc PR        | TODO

[] this needs #112 to be merged first
[] integrate things from #95 here.