Fix subscribe

[lukabratos]

What?

Move ⬇️ out of the if Device.idAlreadyPresent() statement.

persistenceService.persist(interest: interest)
            localStorageQueue.async {
                persistenceService.persist(interest: interest)
                completion()
            }

---

CC @pusher/mobile

[codecov-io]

Codecov Report

Merging #66 into master will increase coverage by 16.04%.
The diff coverage is 100%.

@@             Coverage Diff             @@
##           master      #66       +/-   ##
===========================================
+ Coverage   80.97%   97.02%   +16.04%     
===========================================
  Files          29       16       -13     
  Lines         983      538      -445     
===========================================
- Hits          796      522      -274     
+ Misses        187       16      -171

Impacted Files	Coverage Δ
Tests/SDKTests.swift	100% <100%> (ø)	⬆️
Tests/MetadataTests.swift	89.65% <100%> (ø)	⬆️
Sources/SystemVersion.swift
Sources/Device.swift
Sources/NetworkService.swift
Sources/PublishId.swift
Sources/ReportEventType.swift
Sources/Instance.swift
Sources/DeviceTokenHelper.swift
Sources/PersistenceService.swift
... and 4 more

---

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[luismfonseca]

Add regression test + update changelog :o