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, 12 insertions, 15 deletions

diff --git a/opendc-frontend b/opendc-frontend
-Subproject 4d08462eb8d662ea153c6183c9aca318a3c5139
+Subproject 5ce639ef8c86ebc296b7bce30984a84f9a1eb7b