Add Time Trigger API and client (#153) (#161)

This change adds a timer trigger API, client, and implementation.  Users can trigger a function with a cron-compatible string. 

This change also moves the publisher interface and webhook-based publisher implementation out of kubewatcher and into a separate `publisher` package.

controller/timeTriggerStore.go

@@ -0,0 +1,79 @@
+/*
+Copyrigtt 2017 The Fission 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
+
+    tttp://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 controller
+
+import (
+	"github.com/satori/go.uuid"
+
+	"github.com/fission/fission"
+)
+
+type TimeTriggerStore struct {
+	ResourceStore
+}
+
+func (tts *TimeTriggerStore) Create(tt *fission.TimeTrigger) (string, error) {
+	tt.Metadata.Uid = uuid.NewV4().String()
+	return tt.Metadata.Uid, tts.ResourceStore.create(tt)
+}
+
+func (tts *TimeTriggerStore) Get(m *fission.Metadata) (*fission.TimeTrigger, error) {
+	var tt fission.TimeTrigger
+	err := tts.ResourceStore.read(m.Name, &tt)
+	if err != nil {
+		return nil, err
+	}
+	return &tt, nil
+}
+
+func (tts *TimeTriggerStore) Update(tt *fission.TimeTrigger) (string, error) {
+	tt.Metadata.Uid = uuid.NewV4().String()
+	return tt.Metadata.Uid, tts.ResourceStore.update(tt)
+}
+
+func (tts *TimeTriggerStore) Delete(m fission.Metadata) error {
+	typeName, err := getTypeName(fission.TimeTrigger{})
+	if err != nil {
+		return err
+	}
+	return tts.ResourceStore.delete(typeName, m.Name)
+}
+
+func (tts *TimeTriggerStore) List() ([]fission.TimeTrigger, error) {
+	typeName, err := getTypeName(fission.TimeTrigger{})
+	if err != nil {
+		return nil, err
+	}
+
+	bufs, err := tts.ResourceStore.getAll(typeName)
+	if err != nil {
+		return nil, err
+	}
+
+	triggers := make([]fission.TimeTrigger, 0, len(bufs))
+	js := JsonSerializer{}
+	for _, buf := range bufs {
+		var tt fission.TimeTrigger
+		err = js.deserialize([]byte(buf), &tt)
+		if err != nil {
+			return nil, err
+		}
+		triggers = append(triggers, tt)
+	}
+
+	return triggers, nil
+}