Replaced `BadRequest` with `MethodNotAllowed` for unsupported methods.
Replaced `BadRequest` with `MethodNotAllowed` for unsupported methods.

Review: https://reviews.apache.org/r/40906

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