CYB-195.  Do not clobber user share preferences on app start.

The initial user import code does not need to set 'share' to false, that is the default in the database.  As other attributes used to update the user are coming from canvas, this makes no sense to be updated in the import.

[CYB-195. Apache restart reset student share to false ](https://jira.ets.berkeley.edu/jira/browse/CYB-195)