allow exporting dates as timestamps grom GLOBAL STATUS
allow exporting dates as timestamps grom GLOBAL STATUS

Signed-off-by: mamiller <ad151ef8e9db4befa1d66775d3e7e3f1bfff6820@rosettastone.com>

roman-vynar/mysqld_exporter,prometheus/mysqld_exporter,prometheus/mysqld_exporter,roman-vynar/mysqld_exporter