MT fixes to provide initial support for tenant-specific guests

- explicit guest access is required, such as "guest@tenant1" (note: implicit/anonymous guest access can only login to the default domain)
- also fixes issue with "Show All" users, when logged in as a tenant admin

git-svn-id: https://svn.alfresco.com/repos/alfresco-enterprise/alfresco/HEAD/root@7748 c4b6b30b-aa2e-2d43-bbcb-ca4b014f7261

source/java/org/alfresco/repo/tenant/TenantService.java

@@ -42,6 +42,8 @@ public interface TenantService
 {
     public static final String SEPARATOR = "@";
     
+    public static final String DEFAULT_DOMAIN = "";
+    
     public static final String ADMIN_BASENAME = "admin";
     
     public NodeRef getName(NodeRef nodeRef);
@@ -80,6 +82,8 @@ public interface TenantService
     
     public boolean isTenantName(String name);
 
+    public String getUserDomain(String username);
+    
     public String getCurrentUserDomain();
     
     public String getDomain(String name);