CYB-74, CYB-86.  Adding background worker process and first worker

https://jira.ets.berkeley.edu/jira/browse/CYB-86
( and https://jira.ets.berkeley.edu/jira/browse/CYB-74 )
* Uses the sidekiq background processing framework, and sidetiq for period job execution
* Adds a thor task to kick the job off manually
* Requires Redis
* Updates README.md file with latest instructions