Queueing, prepping to fetch

A lot more to go, but this is the core.

Need to think about how to test the queue handlers.

internal/types/jobs.go

@@ -0,0 +1,22 @@
+package types
+
+import "encoding/json"
+
+type Job interface {
+	AsJson() string
+}
+
+// Used by all of the jobs.
+func _as_json(j Job) string {
+	as_json, _ := json.Marshal(j)
+	return string(as_json)
+}
+
+type EntreJob struct {
+	URL             string          `json:"url"`
+	UpdateFrequency UpdateFrequency `json:"update_frequency"`
+}
+
+func (ej *EntreJob) AsJson() string {
+	return _as_json(ej)
+}