Deprecation warning with saga 0.15.x (all([...effects]) - parallel effects)

[KrzysztofKarol]

With https://github.com/redux-saga/redux-saga/releases/tag/v0.15.0

all effect - explicit effect for parallel effects, which is exactly what we had been supporting by accepting yielded arrays, so the latter is become deprecated now in favor of this explicitness which nicely maps to the Promise.all API. Please use this from now on

PR: #25

[mhssmnn]

Closed in #25