Added Eric Chung to contributors.yaml.
Added Eric Chung to contributors.yaml.

Review: https://reviews.apache.org/r/57825/

neilconway/mesos,dforsyth/mesos,reneploetz/mesos,reneploetz/mesos,zmalik/mesos,asamerh4/mesos,abudnik/mesos,andschwa/mesos,abudnik/mesos,craimbert/mesos,abudnik/mesos,Gilbert88/mesos,verizonlabs/mesos,neilconway/mesos,Gilbert88/mesos,dforsyth/mesos,reneploetz/mesos,neilconway/mesos,dforsyth/mesos,abudnik/mesos,kaysoky/mesos,verizonlabs/mesos,andschwa/mesos,yuquanshan/customizedMesos,Aman-Jain-14/customizedMesos,zmalik/mesos,andschwa/mesos,abudnik/mesos,kaysoky/mesos,jpeach/mesos,reneploetz/mesos,gsantovena/mesos,zmalik/mesos,dforsyth/mesos,verizonlabs/mesos,chhsia0/mesos,jpeach/mesos,andschwa/mesos,asamerh4/mesos,Aman-Jain-14/customizedMesos,yuquanshan/customizedMesos,kaysoky/mesos,asamerh4/mesos,kaysoky/mesos,craimbert/mesos,gsantovena/mesos,gsantovena/mesos,neilconway/mesos,verizonlabs/mesos,kaysoky/mesos,asamerh4/mesos,dforsyth/mesos,zmalik/mesos,andschwa/mesos,chhsia0/mesos,jpeach/mesos,Gilbert88/mesos,asamerh4/mesos,verizonlabs/mesos,yuquanshan/customizedMesos,craimbert/mesos,craimbert/mesos,andschwa/mesos,abudnik/mesos,kaysoky/mesos,jpeach/mesos,jpeach/mesos,verizonlabs/mesos,zmalik/mesos,yuquanshan/customizedMesos,Gilbert88/mesos,Aman-Jain-14/customizedMesos,reneploetz/mesos,neilconway/mesos,gsantovena/mesos,jpeach/mesos,dforsyth/mesos,Aman-Jain-14/customizedMesos,verizonlabs/mesos,zmalik/mesos,yuquanshan/customizedMesos,gsantovena/mesos,craimbert/mesos,abudnik/mesos,neilconway/mesos,dforsyth/mesos,reneploetz/mesos,chhsia0/mesos,Gilbert88/mesos,gsantovena/mesos,chhsia0/mesos,chhsia0/mesos,craimbert/mesos,Aman-Jain-14/customizedMesos,asamerh4/mesos,neilconway/mesos,Gilbert88/mesos,asamerh4/mesos,andschwa/mesos,kaysoky/mesos,craimbert/mesos,Aman-Jain-14/customizedMesos,reneploetz/mesos,gsantovena/mesos,yuquanshan/customizedMesos,jpeach/mesos,chhsia0/mesos,Gilbert88/mesos,zmalik/mesos,Aman-Jain-14/customizedMesos,chhsia0/mesos,yuquanshan/customizedMesos