Use libadblockplus update checker

src/shared/Utils.cpp

Index: src/shared/Utils.cpp
===================================================================
--- a/src/shared/Utils.cpp
+++ b/src/shared/Utils.cpp
@@ -15,16 +15,31 @@ namespace
     OSVERSIONINFOEX osvi;
     ZeroMemory(&osvi, sizeof(OSVERSIONINFOEX));
     osvi.dwOSVersionInfoSize = sizeof(OSVERSIONINFOEX);
     GetVersionEx(reinterpret_cast<LPOSVERSIONINFO>(&osvi));
     return osvi.dwMajorVersion >= 6;
   }
 }
 
+std::string ToUtf8String(std::wstring str)
+{
+  size_t length = str.size();
+  if (length == 0)
+    return std::string();
+
+  DWORD utf8StringLength = WideCharToMultiByte(CP_UTF8, 0, str.c_str(), length, 0, 0, 0, 0);
+  if (utf8StringLength == 0)
+    throw std::runtime_error("Failed to determine the required buffer size");
+
+  std::string utf8String(utf8StringLength, '\0');
+  WideCharToMultiByte(CP_UTF8, 0, str.c_str(), length, &utf8String[0], utf8StringLength, 0, 0);
+  return utf8String;
+}
+
 std::wstring GetAppDataPath()
 {
   if (appDataPath.empty())
   {
     if (IsWindowsVistaOrLater())
     {
       WCHAR* pathBuffer;
       if (FAILED(SHGetKnownFolderPath(FOLDERID_LocalAppDataLow, 0, 0, &pathBuffer)))