Update HISTORY.md with 2.3.0 and 2.4.0

HISTORY.md

@@ -1,5 +1,37 @@
 # History
 
+## 2.4.0 (2017-02-03)
+
+The 2.4.0 release contains the following API Changes:
+
+- Add `SimulateUplink` RPC to Application Manager API. Can be used to test (for example) integrations or external applications.
+- Add "confirmed" field to DownlinkMessage
+- Add "is_retry" field to UplinkMessage
+
+Other changes:
+
+- Use `gogoproto` instead of regular `proto` (and use it in jsonpb marshaling for HTTP API)
+- Better handling of confirmed uplink
+- Add support for confirmed downlink
+- Try to create AMQP exchange instead of crashing
+- Add TLS support to MQTT Client
+- Add validation for DataRates
+- Add more metadata to log messages
+
+## 2.3.0 (2017-01-20)
+
+The 2.3.0 release contains the following API Changes:
+
+- Added pagination with `limit` and `offset` in gRPC metadata or HTTP query string
+- Handler Devices "List" operation returns total number of devices in gRPC Header
+
+Other changes:
+
+- Use `TheThingsNetwork/go-utils/log` instead of `apex/log`
+- Use `TheThingsNetwork/go-utils/encoding` for Redis Maps and optimize list operations
+- Don't crash on unexpected Otto panics
+- Testing payload functions in `ttnctl`
+
 ## 2.2.0 (2017-01-16)
 
 The 2.2.0 release contains the following API Changes: