Fixed endpoint help leak upon process termination.
Fixed endpoint help leak upon process termination.

Previously, the global help process would retain the help information
of processes even after they were termianted.

This commit adds code to remove these help strings.

Review: https://reviews.apache.org/r/43215/

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