Add goheader linter

.golangci.yml

@@ -10,7 +10,7 @@ linters:
     - gocritic
     - gocyclo
     - goerr113
-#    - goheader # TODO: Needs config
+    - goheader
     - gofmt
     - goimports
     - golint
@@ -25,6 +25,8 @@ linters:
 linter-settings:
   nestif:
     min-complexity: 6
+  goheader:
+    template-path: code-hesader-template.txt
 
 issues:
   exclude-rules:

code-header-template.txt

@@ -0,0 +1,15 @@
+Vikunja is a to-do list application to facilitate your life.
+Copyright 2018-2020 Vikunja and contributors. All rights reserved.
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <https://www.gnu.org/licenses/>.