Add and update copyright notices

author/author.go

@@ -1,5 +1,5 @@
 /*
- * Copyright © 2018 A Bunch Tell LLC.
+ * Copyright © 2018-2020 A Bunch Tell LLC.
  *
  * This file is part of WriteFreely.
  *

oauth_signup.go

@@ -1,3 +1,13 @@
+/*
+ * Copyright © 2020 A Bunch Tell LLC.
+ *
+ * This file is part of WriteFreely.
+ *
+ * WriteFreely is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, included
+ * in the LICENSE file in this source code package.
+ */
+
 package writefreely
 
 import (

oauth_slack.go

@@ -1,3 +1,13 @@
+/*
+ * Copyright © 2020 A Bunch Tell LLC.
+ *
+ * This file is part of WriteFreely.
+ *
+ * WriteFreely is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, included
+ * in the LICENSE file in this source code package.
+ */
+
 package writefreely
 
 import (