Release 0.2.0

- new language: go
- new shops: cybertek.fr, mediamarkt.ch
- deprecated shops: alternate.be, minershop.eu
- improved database transaction management
- better web parsing library (ferret, requires headless chrome browser)
- include or exclude products by applying regex on their names
- check for PID file to avoid running the bot twice
- hastags are now configurable

Signed-off-by: Julien Riou <julien@riou.xyz>

notifier.go

@@ -0,0 +1,9 @@
+package main
+
+import "time"
+
+// Notifier interface to notify when a product becomes available or is sold out again
+type Notifier interface {
+	NotifyWhenAvailable(string, string, float64, string, string) error
+	NotifyWhenNotAvailable(string, time.Duration) error
+}