[Halld-offline] Automatic builds on new pull request working again.

[Mark Ito]

Needed to fix a mounting issue with the /home partition on 
sandd1.jlab.org and tweak the configuration of the relevant line in the 
authorized_keys file for the gluex account. See

   https://markito3.wordpress.com/2017/08/23/pull-request-problem/

for some of the details.

-- 
Mark Ito, marki at jlab.org, (757)269-5295