Current, scan_checked_replset.js makes an assumption that the authenticationDatabase for connections will always be `admin`.  This is often true, but for externally managed users (e.g. LDAP), it is not.

Modify all uses of `auth()` in the script to be invoked on the `mongo` connection instance, and ensure that authInfo has a default value of `admin` for the db field.

e.g. In various places:

-   db.getSiblingDB('admin').auth(authInfo);
+   db.getMongo().auth(authInfo); 

and at the bottom of the script:

 var authInfo;
+authInfo.db = authInfo.db || 'admin';

Secondly, it is currently impossible to use TLS when opening new connections to cluster members.  To accomodate this, we need to either extract TLS info from the base connection or provide a `tlsInfo` struct (similar to authInfo) and consctruct a meaningful mongodb:// URI when opening new connections, or we need to simply allow the user to specify arbitrary URI parameters and append them to the constructed mongodb:// URI.