Refactored update_dag.py
Prototyped use of message queue.
Prototyped cli message queue tool.
Removed smq line in requirements.

Will need to install manually.
Updated travis ci file.
Updated setup.py
Fixed directory in travis ci file.
Merge branch 'master' into v1.7
Increased database timeout in master to 7 seconds.
Added a flag in gsub to set the message queue file explicitly.

SQLite3 stays locked on shared storage, e.g. cifs/nfs.
Changed shell update to use its pid in its sender name.
Fixed string representation of uuid.
Added missing "="
Added check to prevent shell_update from running this it shouldn't.
Fixed concating process
Moved command check.
Prototyped manual use of threads in dag.shell.

multiprocessing in python is terrible.
Replaced kill() with KILL_SIGNAL.
Patched in state updates.
Changed where process state is updated. Allowed non-Shell processes to
be set to success if they finish without setting their own status.