* Generalize switch between different datasources.
* Fix previous migration since slice model changed
* Fix warm up cache and other small stuff
* Adding modules and datasources through config
* Replace tabs w/ spaces
* Fix other style issues
* Change add method for SliceModelView to pick the first non-empty ds
* Remove tests on slice add redirect
* Change way of db migration
* Fix styling
* Fix create slice
* Small fixes
* Fix code climate check
* Adding notes on how to create new datasource in CONTRIBUTING.md
* Fix last merge
* A commit just to trigger travis build again
* Add migration to merge two heads
* Fix codeclimate
* Simplify source_registry
* Fix codeclimate
* Remove all getter methods