BalsamJob Model stores fractional seconds in state history
Serial experiment: independent hello world jobs. Auto-writes CDFs to
benchmark data directory.

Init Postgres backend works; added "balsam which"; Can run sqlite/Postgres backends from "balsam dbserver"; Upped timeouts/queue depths for ZMQ Sqlite server

workers(nodes) available to Balsam; useful for running benchmarks

* timing capabilities built in to MPIEnsemble runner and MPIRunner
Now successful job runs should have an elapsed runtime in seconds
added to the field runtime_seconds

* Refactored utilites for automated testing and benchmarking

Job PK and version are properly updated with sqlite_client save method. test runner works with both save methods

* User explicitly creates balsam DB directory with "balsam init"
* User launches DB server with "balsam dbserver"
* user_settings is vastly simplified...moved all configuration logic
into django_config module
* Database is auto-configured on django startup; will connect to DB
server automatically if client

* user kill works even when a kill save() takes a long time in flight
  and some other processing happens first
* updated functional tests
* all tests passing on Theta, Cooley

all back into development branch.

Merge remote-tracking branch 'origin/theta-changes' into develop

Added test cases