Catch all vim exceptions in disk_detach (#460)
Catch all vim exceptions in disk_detach (#460)

Return error message from exception, and logs a warning with traceback.
Also change logging in findVMByUuid to be warning (since we retry after the failure)

Fixes https://github.com/vmware/docker-volume-vsphere/issues/381
BaluDontu/docker-volume-vsphere,ashahi1/docker-volume-vsphere,brunotm/docker-volume-vsphere,govint/docker-volume-vsphere,pshahzeb/vsphere-storage-for-docker,lipingxue/docker-volume-vsphere,govint/docker-volume-vsphere,BaluDontu/docker-volume-vsphere,lipingxue/docker-volume-vsphere,venilnoronha/docker-volume-vsphere,venilnoronha/docker-volume-vsphere,BaluDontu/docker-volume-vsphere,govint/docker-volume-vsphere,brunotm/docker-volume-vsphere,shivanshu21/docker-volume-vsphere,brunotm/docker-volume-vsphere,shuklanirdesh82/docker-volume-vsphere,venilnoronha/docker-volume-vsphere,BaluDontu/docker-volume-vsphere,shuklanirdesh82/docker-volume-vsphere,venilnoronha/docker-volume-vsphere,shivanshu21/docker-volume-vsphere,luomiao/docker-volume-vsphere,ashahi1/docker-volume-vsphere,ashahi1/docker-volume-vsphere,pshahzeb/vsphere-storage-for-docker,luomiao/docker-volume-vsphere,venilnoronha/docker-volume-vsphere,brunotm/docker-volume-vsphere,BaluDontu/docker-volume-vsphere,luomiao/docker-volume-vsphere,brunotm/docker-volume-vsphere,shivanshu21/docker-volume-vsphere,pshahzeb/vsphere-storage-for-docker,lipingxue/docker-volume-vsphere,BaluDontu/docker-volume-vsphere,pshahzeb/vsphere-storage-for-docker,brunotm/docker-volume-vsphere,ashahi1/docker-volume-vsphere,govint/docker-volume-vsphere,luomiao/docker-volume-vsphere,shuklanirdesh82/docker-volume-vsphere,shuklanirdesh82/docker-volume-vsphere,shuklanirdesh82/docker-volume-vsphere,shivanshu21/docker-volume-vsphere,lipingxue/docker-volume-vsphere,govint/docker-volume-vsphere,luomiao/docker-volume-vsphere,pshahzeb/vsphere-storage-for-docker,shivanshu21/docker-volume-vsphere,pshahzeb/vsphere-storage-for-docker,ashahi1/docker-volume-vsphere,shivanshu21/docker-volume-vsphere,ashahi1/docker-volume-vsphere,lipingxue/docker-volume-vsphere,lipingxue/docker-volume-vsphere,govint/docker-volume-vsphere,luomiao/docker-volume-vsphere,BaluDontu/docker-volume-vsphere,venilnoronha/docker-volume-vsphere,shuklanirdesh82/docker-volume-vsphere