Do not check for a new version by default.

diff --git a/src/common.cpp b/src/common.cpp
index cbfabd3..9eb8eaf 100644
--- a/src/common.cpp
+++ b/src/common.cpp
@@ -74,7 +74,7 @@ GlobPreferences::GlobPreferences(void)
     store_additional_data_on_disk(true),
     certificate_validation_date(DOWNLOAD_DATE),
     check_crl(true),
-    check_new_versions(true),
+    check_new_versions(false),
     send_stats_with_version_checks(false),
     download_on_background(false),
     timer_value(10),