Migrate to redux-pouchdb-plus to resolve race condition

[danobot]

This is required to work around #71. The library used to load data into the redux store (redux-pouchdb) is unmaintained.
See linked issue for details.

This issue is blocked by the fact redux-pouchdb-plus does not support collection reduces, which Notorious uses exclusively.

Alternative redux-pouchdb libraries:

• https://github.com/yanick/redux-persist-pouchdb