feat: Implement Scheduler Reference Architecture

This change implements the parts of the Datacenter Scheduling Reference
Architecture as published in SC18.

This commit consists of changes to the database schema such as:

- **Removal of `parallelizability` column in `Task`**
  This field was not used by the simulator and we opted to use a field
  describing the amount of cores the task can run on instead.
- **Removal of `task_id` column in `MachineState`**
  This field did not make sense anymore now that a machine can run
  multiple tasks. Fortunately, this field is not used in the frontend.

1 files changed, 19 insertions, 5 deletions

diff --git a/opendc-web-server b/opendc-web-server
-Subproject b87faa0bccf661a2b6a948d9420d52a19a63d9a
+Subproject 9a2a98548ab50217a78d433a13da72af3001a78