Iterate frameworks successively to save concat
Iterate frameworks successively to save concat

`concat` concatenates two Arrays and returns a new Array. `frameworks`
and `completed_frameworks` can be iterated successively to save
allocation of a new Array that is thrown away after finding the current
framework.

Review: http://reviews.apache.org/r/12834

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