Add initializer to ExtensionBuilder

Author: pkasila

Sources/CEExtensionKit/ExtensionInterface.swift

@@ -12,6 +12,10 @@ public protocol ExtensionInterface {
 }
 
 open class ExtensionBuilder: NSObject {
+    required public override init() {
+        super.init()
+    }
+
     /// Builds extension with API
     /// - Parameter withAPI: the API implementation itself
     open func build(withAPI api: ExtensionAPI) -> ExtensionInterface {