Made the master detection log messages more verbose.
Made the master detection log messages more verbose.

This change increases the verbosity of master detection messages
in the scheduler library to be in sync with the verbosity level
in the driver.

Review: https://reviews.apache.org/r/46722/

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