* Database isolation: Balancer
Remove naive Balancer
remove debugging lines
Thread dax.Transaction through Controller
Change role to roleType
Swap out Balancer interface with new one
Standardize InvalidTransaction error
Add some interface comments
* Remove type.Worker; replace with type.Address
* Remove database validate from Queryer
This is already being handled in the `CreateTable()` method. Prior
to doing that validation, we were getting a panic, but that's no longer
the case.
* Remove dax.TableQualifier; replace with dax.QualifiedDatabaseID
* Update IDK test to create database
* Make interfaces more specific than "MDS"
- Introduce `dax.Schemar` interface
- Introduce `dax.Noder` interface
- The rest is generally to standardize on the new interfaces.
- Remove `pilosa.SchemaInfoAPI` interface
- Move `TranslateNode` and `ComputeNode` types from controller to dax package
- Remove `queryer.FeatureBaseImporter`
- Remove `queryer.MDS` interface
- Remove `queryer.Importer` interface
- Identify types using an "MDS" interface and split into Noder/Schemar as necessary
- Changed `Queryer.orchestrator` to a `map[qual]*qualifiedOrchestrator` because we can't share an orchestrator across quals
* Convert orchestrator to use TableKeyer
