Supports adding trusted sources from SourcesViewController

Previously, only the beta version of AltStore could add sources. Now, the public version supports adding explicitly “trusted” sources, while the beta version can continue to add any source.

AltStoreCore/Extensions/UserDefaults+AltStore.swift

@@ -37,6 +37,8 @@ public extension UserDefaults
     
     @NSManaged var patchedApps: [String]?
     
+    @NSManaged var trustedSourceIDs: [String]?
+    
     var activeAppsLimit: Int? {
         get {
             return self._activeAppsLimit?.intValue

AltStoreCore/Model/Source.swift

@@ -33,10 +33,6 @@ public extension Source
     #endif
     
     #endif
-    
-    static let exampleIdentifier = "io.altstore.example"
-    
-    static let allowedIdentifiers: Set<String> = [exampleIdentifier]
 }
 
 @objc(Source)