[FIX] Fix login with Meteor saving an object as email address

[sampaiodiego]

@RocketChat/core

We were saving an object for emails.address user's property for Meteor's OAuth as shown bellow:

{
    "_id" : "fAkeId",
    "type" : "user",
    "name" : "fakename",
    "emails" : [ 
        {
            "address" : {
                "address" : "[email protected]",
                "verified" : true,
                "primary" : true
            },
            "verified" : true
        }
    ],
    "roles" : [ 
        "user"
    ]
}

This PR is to get only the primary email address from Meteor's OAuth and also fixes problems related to getUsernameSuggestion because address property was not a string.