prepare for release of OSS version 0.19.0 (#6061)

fbshipit-source-id: 1f1cf02

prepare for release of OSS version 0.18.2 (#5764)

fbshipit-source-id: 17ab349

prepare for release of OSS version 0.18.1 (#5694)

fbshipit-source-id: e480da1

prepare for release of OSS version 0.18.0 (#5643)

fbshipit-source-id: 15d60a9

prepare for release of OSS version 0.17.2 (#5515)

fbshipit-source-id: c946d20

prepare for release of OSS version 0.17.1 (#5485)

fbshipit-source-id: 1c0b648

prepare for release of OSS version 0.17.0 (#5435)

fbshipit-source-id: 4e6db9a

prep for 0.16.0 release (#5347)

fbshipit-source-id: 2850b42

[rotor/xds/poller] bigger example certs (#5286)

use 4096-bit certs, for better browser compatability

fbshipit-source-id: 46642c4