Add exception hook to teuthology-worker
Add exception hook to teuthology-worker

Workers processes are dying occasionally, and this should cause the
exceptions to be logged.

Signed-off-by: Zack Cerza <f801c831581d4150a2793939287636221d62131e@inktank.com>

michaelsevilla/teuthology,dmick/teuthology,caibo2014/teuthology,SUSE/teuthology,zhouyuan/teuthology,tchaikov/teuthology,michaelsevilla/teuthology,ktdreyer/teuthology,dreamhost/teuthology,ivotron/teuthology,SUSE/teuthology,yghannam/teuthology,tchaikov/teuthology,ktdreyer/teuthology,yghannam/teuthology,caibo2014/teuthology,SUSE/teuthology,t-miyamae/teuthology,ceph/teuthology,dmick/teuthology,ivotron/teuthology,t-miyamae/teuthology,dmick/teuthology,robbat2/teuthology,robbat2/teuthology,zhouyuan/teuthology,ceph/teuthology,dreamhost/teuthology