Fix connector naming in strict mode

In strict mode, creating properties on strings is not allowed.
As a result, creating a new datasource fails with the following
error:

    TypeError: Cannot create data source "db":
    Cannot create property 'name' on string 'mongodb'

In this commit, we fix the code to assign the connector name only
if the connector is an object (not a string).

Add "returnOnlyRoleNames" option to Role.getRoles

Currently the return type of Role.getRoles() method is inconsistent:
role names are returned for smart roles and role ids are returned for
static roles (configured through user-role mapping).

This commit adds a new option to Role.getRoles() allowing the caller
to request role names to be returned for all types of roles.

lib/application.js

@@ -423,7 +423,7 @@ function dataSourcesFromConfig(name, config, connectorRegistry, registry) {
         config.connector = require(connectorPath);
       }
     }
-    if (!config.connector.name)
+    if (config.connector && typeof config.connector === 'object' && !config.connector.name)
       config.connector.name = name;
   }