Database Manager

done:
+ master.sql as resource
+ implemented incremental database changes also for Master
+ dbUp sql script variables implemented
+ improved database handling and creation code
+ simpified database creation
+ almost all Database and Tenant creation moved to DatabaseManager.cs (rest code marked with TODO)
+ Unattended install of master can be performed by settings in appsettings.json
+ Improved IsInstalled checking
+ Removed DBSchema field from Tenant
+ Default database and site creation moved to Program.Main

Oqtane.Shared/Shared/InstallConfig.cs

@@ -0,0 +1,12 @@
+namespace Oqtane.Shared
+{
+    public class InstallConfig
+    {
+        public string Alias { get; set; }
+        public string ConnectionString { get; set; }
+        public string HostUser { get; set; }
+        public string Password { get; set; }
+        public string HostEmail { get; set; }
+        public bool IsMaster { get; set; }
+    }
+}