Support none database type to disable stats/telemetry

Fixes #21

database/none/none.go

@@ -0,0 +1,23 @@
+package none
+
+import (
+	"github.com/librespeed/speedtest/database/schema"
+)
+
+type None struct{}
+
+func Open(_ string) *None {
+	return &None{}
+}
+
+func (n *None) Insert(_ *schema.TelemetryData) error {
+	return nil
+}
+
+func (n *None) FetchByUUID(_ string) (*schema.TelemetryData, error) {
+	return &schema.TelemetryData{}, nil
+}
+
+func (n *None) FetchLast100() ([]schema.TelemetryData, error) {
+	return []schema.TelemetryData{}, nil
+}