Emit error events when a commit fails. This fixes single_commit_error testcase partially.
Emit error events when a commit fails. This fixes single_commit_error
testcase partially.

Count sink engine errors and  then engine error event if at least one
sink error appeared. This is needed to let the OSyncEngine fail and
throw an error. Otherwise the sync would finish as "successful".



git-svn-id: e31799a7ad59d6ea355ca047c69e0aee8a59fcd3@3019 53f5c7ee-bee3-0310-bbc5-ea0e15fffd5e

ianmartin/opensync,ianmartin/opensync