User auth

[petermenzies]

• use shinymanager package to password protect app using AES encrypted SQLite database
• create multiple access levels: regular user, write-access user, and admin. Admin has access to a dashboard from which passwords can be reset and user logs can be viewed. Write-access users can make changes to targets and in the future will be able to make corrections to the dataset.
• This will negate the need to go through Nick to add users to the LDAP group