johngmyers: Promote channel alpha to stable

JobBuild
12050
07-27 04:32
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pull-kops-verify-generated 1419917153083068416 1419886644961480704 1419878247126011904
pull-kops-verify-gofmt 1419917153238257664 1419886645083115520 1419878247256035328
pull-kops-verify-gomod 1419917153150177280 1419886645020200960 1419878247167954944
pull-kops-verify-govet 1419917153276006400 1419886645120864256 1419878247297978368
pull-kops-verify-staticcheck 1419917153313755136 1419886645150224384 1419878247335727104