Deduplicate conversations before passing to redux
Deduplicate conversations before passing to redux

Receiving a single message on conversations triggers ~4 updates.
However, since `.format()` is called on next tick - the value is going
to be the same regardless of which particular update triggered it. Batch
conversations and de-duplicate them before passing to redux to save
time.
nrizzio/Signal-Desktop,nrizzio/Signal-Desktop,nrizzio/Signal-Desktop,nrizzio/Signal-Desktop