Updated CHANGELOG for 0.26.0 release to include API change for "/frameworks" master endpoint.
Updated CHANGELOG for 0.26.0 release to include API change for
"/frameworks" master endpoint.

Review: https://reviews.apache.org/r/39922

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