Add extra handler for generic notifications

(instead of misusing onSMS handler). Pebble still does that,
but not everybody has to.

Small step for #53

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/AbstractBTDeviceSupport.java

@@ -63,6 +63,12 @@ public abstract class AbstractBTDeviceSupport extends AbstractDeviceSupport {
         sendToDevice(bytes);
     }
 
+    @Override
+    public void onGenericNotification(String title, String details) {
+        byte[] bytes = gbDeviceProtocol.encodeGenericNotification(title, details);
+        sendToDevice(bytes);
+    }
+
     @Override
     public void onSetTime(long ts) {
         byte[] bytes = gbDeviceProtocol.encodeSetTime(ts);

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/EventHandler.java

@@ -5,6 +5,8 @@ public interface EventHandler {
 
     void onEmail(String from, String subject, String body);
 
+    void onGenericNotification(String title, String details);
+
     void onSetTime(long ts);
 
     void onSetCallState(String number, String name, GBCommand command);

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/miband/MiBandSupport.java

@@ -126,6 +126,11 @@ public class MiBandSupport extends AbstractBTLEDeviceSupport {
         performDefaultNotification("email received");
     }
 
+    @Override
+    public void onGenericNotification(String title, String details) {
+        performDefaultNotification("generic notification received");
+    }
+
     @Override
     public void onSetTime(long ts) {
         try {

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/pebble/PebbleProtocol.java

@@ -224,6 +224,11 @@ public class PebbleProtocol extends GBDeviceProtocol {
         return encodeMessage(ENDPOINT_NOTIFICATION, NOTIFICATION_EMAIL, 0, parts);
     }
 
+    @Override
+    public byte[] encodeGenericNotification(String title, String details) {
+        return encodeSMS(title, details);
+    }
+
     @Override
     public byte[] encodeSetTime(long ts) {
         if (ts == -1) {

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/protocol/GBDeviceProtocol.java

@@ -12,6 +12,10 @@ public abstract class GBDeviceProtocol {
         return null;
     }
 
+    public byte[] encodeGenericNotification(String title, String details) {
+        return null;
+    }
+
     public byte[] encodeSetTime(long ts) {
         return null;
     }