we now requre Redis
added instructions for installing Redis
added questions for redis_port
FarmServer gains a hostname column, so farm processes know where the server is
new methods log_dir(), redis_port() and redis()
when creating the farmserver, set the hostname
SidToSub now updates assignment_time whenever sub_id is changed, even when it is undefed
reimplemented submission assignment to storing sub ids in a Redis queue and having handlers pop them off
Merge branch 'develop' of /software/vertres/git/origin/vr-pipe into feature/redis
since contention issues have been resolved, the submission handler watcher can start immediately
make sure the redis server is alive while we are, and kill it when we exit
disconnect before and after opening a file
Merge branch 'feature/redis' into develop