Reducing the initial readiness probe delay from 5 secs to 1 sec (dapr…

…#1363)

Also reducing the timeout from 5 to 3 secs

Add 0.5.1 release note (dapr#1286)

Small changes in release-0.5 (dapr#1255)

Small changes in release-0.5

Remove actor id agg (dapr#1250)

Fixing the issue of injector metrics initialization (dapr#1245)

Fix wrong error handle in injector (dapr#1241)

* Fix overwritten error in injector

* fix typo

* add unit-test

* add one tc

Merge branch 'release-0.4' of github.com:dapr/dapr into release-0.4