added an option to suppress warning messages

Change-Id: Ic34e9886f468b94589d8ed70fb548cc76c008d25
changed suppressWarnings flag to warnings, defaults to true

Change-Id: If49071b78bdb8c308934a313784e5802c9eff3e3
Merge pull request #4 from kamicane/master

replace performance-now with microseconds for prettier output.
Merge pull request #2 from jordalgo/master

added an option to suppress warning messages
the defaultPath config should not get written if there is no option