Mephisto

Minor version update
This release primarily serves to help with the transition from hydra 1.0 to 1.1, though also includes some additional fixes, especially for ParlAI tasks.
This release also includes `BlueprintMixin`s, which serve as an easier way to inject first-class features into blueprints, and to provide shared functionality across otherwise disjoint tasks.
Key changes:
- Blueprint Mixin refactor, and the `ScreenTaskRequired` mixin (582, 573, 566)
- Compensation HIT launch script (586)
- PyPI Release prep (548)
- ParlAI Onboarding conversion fix, and other bugfixes (573, 554, 555)
- JS Package reorg (565, 574, 570)
- Hydra migration fixes (587)
- Other bugfixes (535, 547, 560)

Notices
- The upgrade to Hydra 1.1 (494) means that previous scripts may not function properly. Remediation steps for this are included in 529.
- The old method of directly initializing Mephisto data model elements (such as `Unit`s and `Agent`s) is being changed to `<Class>.get(db, db_id)` rather than a direct constructor. Both are supported for now, but the old version will be deprecated in 1.0.

Contents
- This version release primarily focuses around our upgrade to hydra 1.1 (494).
- Hydra 1.1 means we can now specify profiles for common launch patterns between jobs (496).
- Deprecating direct data model initialization to move off of metaclasses in 1.0 (437).
- Stability improvements - better state tracking for MTurk units (527)
- UX improvements - easier local development of static react tasks (509), centralizing review utilities for scripts (526), better messaging for unexpected behaviors (528, 530)

This release is fairly minor, including fixes to Botocore and a number of other underlying dependencies.

Also included are 486 and 489, which aim to improve detection of disconnects with the `HerokuArchitect` and clarify messaging about heroku setup failures.

Summary
This release focuses on Mephisto speedups, including fixes to reduce the runtime of many common operations. Most of these are further reduced by using the (BETA) [`MephistoSingletonDB`](https://github.com/facebookresearch/Mephisto/tree/master/mephisto/abstractions/databases#singletonmephistodb-). In combination, these reduce Mephisto's cpu usage by 90% or more for the same number of active tasks, allowing for increased concurrency.

It also includes a number of bugfixes and stability improvements since January

Included changes
+ `max_num_concurrent_units` option for all Mephisto tasks 405
+ Hook to register callbacks after the completion of a task 339
+ Speedups for interactions requiring the `MTurkProvider` 435
+ Speedups for overall Mephisto operations by no longer loading `AgentState` for every `Agent`, preventing unnecessary data reads. 341
+ Significant speedups using the MephistoSingletonDB 432 441
+ Other speed-related fixes 440
+ Flask option for Heroku router 398
+ Various improvements to HerokuArchitect 403 413 411 418
+ MTurk related bugfixes 382 385 445
+ Other bugfixes 400 421 410 439 443 456

This version removes any references to the old ParlAI-MTurk implementation, as it is soon to be removed entirely from the ParlAI repo.

Contains all of the good changes of [v0.3.1](https://github.com/facebookresearch/Mephisto/releases/tag/v0.3.1) but with one less bad change - shutdowns won't run into the race condition of list iterators changing sizes anymore.