Update importer for Volunteers (permissions)

[bransynluther]

Currently there is an issue when importing volunteers where the email field cannot be pulled in from the CSV field because it is not an attribute on the Volunteer Model. In order to solve this issue, the email field provided in the CSV should be used to first create a user, along with the appropriate permissions see Issue #324 . With this in place, the user email can then be used in the creation of the volunteer, allowing for the DB to be populated with the new entry.

• Create functionality that will pull in the PERMISSIONS provided from the CSV File to be used in the creation of a new user, linked to the volunteer being created.

[maebeale]

Add permission_name as one of the fields that can be imported in the volunteer importer, per volunteer.rb
https://github.com/rubyforgood/voices-of-consent/blob/develop/app/models/volunteer.rb