Password reset

- Add UI
- Add API routes
- Update Cassandra schema
- Update k.h.d.users
- Upgrade clj-http
- Add migration doc
- Redirect to login when password changed.
Merge pull request #171 from MastodonC/feature/password-reset

Feature/password reset
Fixes #162
Merge pull request #172 from MastodonC/feature/sensor-unit-fix

Fixes #162
Fix entity post to /4/entities

To handle things where the project_id is inside the entity rather than
part of the URL.