Migrate to Xorm (#474)

close #234

* Migrate store
* Migrate tests
* Rewrite migrations
* Init fresh DB in on step
* Rm old stuff (meddler, sql files, dead code, ...)

server/model/task.go

@@ -0,0 +1,36 @@
+// Copyright 2021 Woodpecker Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package model
+
+// TaskStore defines storage for scheduled Tasks.
+type TaskStore interface {
+	TaskList() ([]*Task, error)
+	TaskInsert(*Task) error
+	TaskDelete(string) error
+}
+
+// Task defines scheduled pipeline Task.
+type Task struct {
+	ID           string            `xorm:"PK UNIQUE 'task_id'"`
+	Data         []byte            `xorm:"'task_data'"`
+	Labels       map[string]string `xorm:"json 'task_labels'"`
+	Dependencies []string          `xorm:"json 'task_dependencies'"`
+	RunOn        []string          `xorm:"json 'task_run_on'"`
+}
+
+// TableName return database table name for xorm
+func (Task) TableName() string {
+	return "tasks"
+}