updates: we now have a user URL, and an automatic one

So the user can use https, while the automatic does not have to

src/common/updates.cpp

@@ -98,9 +98,9 @@ namespace tools
     return found;
   }
 
-  std::string get_update_url(const std::string &software, const std::string &subdir, const std::string &buildtag, const std::string &version)
+  std::string get_update_url(const std::string &software, const std::string &subdir, const std::string &buildtag, const std::string &version, bool user)
   {
-    static const char base[] = "http://updates.getmonero.org/";
+    static const char *base = user ? "https://downloads.getmonero.org/" : "http://updates.getmonero.org/";
 #ifdef _WIN32
     static const char extension[] = ".zip";
 #else

src/common/updates.h

@@ -33,5 +33,5 @@
 namespace tools
 {
   bool check_updates(const std::string &software, const std::string &buildtag, bool bestnet, std::string &version, std::string &hash);
-  std::string get_update_url(const std::string &software, const std::string &subdir, const std::string &buildtag, const std::string &version);
+  std::string get_update_url(const std::string &software, const std::string &subdir, const std::string &buildtag, const std::string &version, bool user);
 }

src/cryptonote_core/cryptonote_core.cpp

@@ -1107,12 +1107,13 @@ namespace cryptonote
     if (tools::vercmp(version.c_str(), MONERO_VERSION) <= 0)
       return true;
 
-    std::string url = tools::get_update_url(software, subdir, buildtag, version);
+    std::string url = tools::get_update_url(software, subdir, buildtag, version, true);
     MGINFO("Version " << version << " of " << software << " for " << buildtag << " is available: " << url << ", SHA256 hash " << hash);
 
     if (check_updates_level == UPDATES_NOTIFY)
       return true;
 
+    url = tools::get_update_url(software, subdir, buildtag, version, false);
     std::string filename;
     const char *slash = strrchr(url.c_str(), '/');
     if (slash)