Removed private header from the balloon framework.
Removed private header from the balloon framework.

Changes the `statusUpdate` handler to explicitly enumerate terminal
states. Previously, the handler used an internal utility method, which
would not be available if this framework were compiled outside of Mesos.

Review: https://reviews.apache.org/r/46411/

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