Updater loop with period and http route (#240)

* Updater loop with period and http route
* Using DNS over TLS to update servers
* Better logging
* Remove goroutines for cyberghost updater
* Respects context for servers update (quite slow overall)
* Increase shutdown grace period to 5 seconds
* Update announcement
* Add log lines for each provider update start

internal/params/updater.go

@@ -0,0 +1,17 @@
+package params
+
+import (
+	"time"
+
+	libparams "github.com/qdm12/golibs/params"
+)
+
+// GetUpdaterPeriod obtains the period to fetch the servers information when the tunnel is up.
+// Set to 0 to disable
+func (r *reader) GetUpdaterPeriod() (period time.Duration, err error) {
+	s, err := r.envParams.GetEnv("UPDATER_PERIOD", libparams.Default("0"))
+	if err != nil {
+		return 0, err
+	}
+	return time.ParseDuration(s)
+}