Reported time offsets are rounded incorrectly

The time offset reported on GraceDB here and here is casted to an integer before being printed with a generic {} formatter. This causes the offset to be rounded incorrectly, e.g. an offset of 0.99 s would be reported as "about 0 seconds".

The int() conversion should be dropped (or changed to float() if an explicit conversion from LIGOTimeGPS is necessary) and the {0:.3f} formatter should be used instead.