Updated the CHANGELOG for 0.28.1.
Updated the CHANGELOG for 0.28.1.

Review: https://reviews.apache.org/r/45773

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