Rename model IdentityKey -> IdentityRecord
Rename model IdentityKey -> IdentityRecord

Reduce ambiguity in between the record itself, which now stores other
information besides the public key, and its `publicKey` attribute, which
contains an ArrayBuffer of key material.

This model is internal to SignalProtocolStore.

// FREEBIE

nrizzio/Signal-Desktop,nrizzio/Signal-Desktop,nrizzio/Signal-Desktop,nrizzio/Signal-Desktop