Add the EnvUser with tests. Create an Environment user during bootstrap

Added the EnvUser doc

Support for setting the last login time for the EnvUser

Added a factory for adding the envuser

Admin EnvUser gets added at bootstrap time

Removed a couple of attributes from the upgrade package that no longer needed to be there

If it is a tag, call it a tag.  But perhaps you want to do:

```go
    envuuid := st.EnvironTag().Id()
    if envuuid == "" {
        return nil, errors.Errorf("environment not set")
    }
````