OTA updates (#96)

## Summary

* Adds support for OTA
  * Gets latest firmware bin from latest GitHub release
* I have noticed it be a little flaky unpacking the JSON and
occasionally failing to start

src/network/OtaUpdater.h

@@ -0,0 +1,30 @@
+#pragma once
+
+#include <functional>
+#include <string>
+
+class OtaUpdater {
+  bool updateAvailable = false;
+  std::string latestVersion;
+  std::string otaUrl;
+  size_t otaSize = 0;
+
+ public:
+  enum OtaUpdaterError {
+    OK = 0,
+    NO_UPDATE,
+    HTTP_ERROR,
+    JSON_PARSE_ERROR,
+    UPDATE_OLDER_ERROR,
+    INTERNAL_UPDATE_ERROR,
+    OOM_ERROR,
+  };
+  size_t processedSize = 0;
+  size_t totalSize = 0;
+
+  OtaUpdater() = default;
+  bool isUpdateNewer();
+  const std::string& getLatestVersion();
+  OtaUpdaterError checkForUpdate();
+  OtaUpdaterError installUpdate(const std::function<void(size_t, size_t)>& onProgress);
+};