campaignd: Record the hashed passphrase for new uploads

Otherwise no passphrase is recorded into the server config and it
becomes impossible to reupload the add-on without admin assistance.

src/campaign_server/campaign_server.cpp

@@ -720,6 +720,8 @@ void server::handle_upload(const server::request& req)
 			return;
 		}
 
+		const bool existing_upload = campaign != NULL;
+
 		std::string message = "Add-on accepted.";
 
 		if(!version_info(upload["version"]).good()) {
@@ -744,6 +746,10 @@ void server::handle_upload(const server::request& req)
 		(*campaign)["type"] = upload["type"];
 		(*campaign)["email"] = upload["email"];
 
+		if(!existing_upload) {
+			set_passphrase(*campaign, upload["passphrase"]);
+		}
+
 		if((*campaign)["downloads"].empty()) {
 			(*campaign)["downloads"] = 0;
 		}