Flag Former Students in the sync process

[jrjohnson]

Once a student has graduated they tend to have strange entries in the
directory. This adds a place for an LDAP query which will only return
former students and they can then be flagged that way so some mis-match
statuses will be ignored.
Students are never unfledged from this automatically, this has to be
done in the management console UI where they can also be flagged
manually.

Fixes #327

[thecoolestguy]

'Step 2' no longer exists, so this should probably be '2. Post-run Processing' OR the initialization step of the process should be 1, and the rest re-ordered...

[dartajax]

Testing steps ... from the notes on the white board. This could use additional clarification. I hope this makes at least some sense.

This is to be performed in ilios-stage environment.

• Refresh data
• Update Users by setting enabled = 1 and user_sync_ignore = 0 for 2012 Cohort (or other Cohort currently disabled)
• Run cron job (Old Code version)
• Verify these users appear in the Admin Console as exceptions
• Run cron job (New Code version)
• Verify these users do NOT appear in the Admin Console as exceptions
• Change a bunch of email addresses
• Run cron job (New Code version)
• Check the Admin Panel >> Exceptions list for these records
• Change other user attribute (name, MI, UC ID)
• Run cron job (New Code version)
• Verify these users do NOT appear in the Admin Console as exceptions and that the Information got updated with the new data.

updated to fix sql to run to enable users.