CYB-208 CYB-222 CYB-227

Deploy code after a push, once a cron job executes the deploy script
Each execution does at least a "git fetch", and does the deploy if there are changes.

* adds a bin/deploy.sh script to do the deploy (can be called by cron)

This does not address the 'write a cron' job in CYB-227.  But this script can be called by that, so all that is needed is a crontab file to call it.

It also depends on $DOCROOT to be defined, or the apache assets won't get placed correctly.

[CYB-222 Write a simple deploy script](https://jira.ets.berkeley.edu/jira/browse/CYB-222)
[CYB-227 Create shell script and cron job to update dev code](https://jira.ets.berkeley.edu/jira/browse/CYB-227)
[CYB-208 Auto update dev on PR merge ](https://jira.ets.berkeley.edu/jira/browse/CYB-208)