Aiidalab

- Revise installation and update implementation (114).
- Determine remote branch from release line instead of checked out branch (115).
- Implement unit test for app with version that is orphaned commit (117).
- Fix/recover from detached head state (116).
- Use the number sign '' instead of '' to indicate release line (118).
- Bump requirements (119).

- Move all the widgets to aiidalab-home app (103)
- Add unit tests (108)
- Add readthedocs (109, 110). The documentation is available here: https://aiidalab.readthedocs.io
- Update packages (111)