* export metadata without nulls, empty arrays
* property tests for 'ReplaceMetadata' using QuickCheck
-> Derive Arbitrary class for 'ReplaceMetadata' dependant types
* reduce property test cases number to 30
QuickCheck generates the `ReplaceMetadata` value really large
for higher number test cases. Encoded JSON for such values is large and
consumes more memory. Thus, CI is giving up while running property
tests.
* circle-ci: Add property tests as saperate job
* add no command mode to tests
* add yaml.v2 to go mod
* remove indirect comment for yaml.v2 dependency
* save permissions, relationships and collections in catalog with 'is_system_defined'
* Use common stanzas in the .cabal file
* Refactor migration code into lib instead of exe
* Add new server test suite that exercises migrations
* Make graphql-engine clean succeed even if the schema does not exist
