Adjust timestamps based on hotspot_log.time_ms

[mjmeehan]

Timestamps in timeline output are displayed relative to the start time of the process. This is because stamp entries are marked as of the start time of the JVM. Adjust these relative timestamps by the timestamp recorded in the <hotspot_log time_ms='1519794663869'> tag.

Essentially, instead of just converting stamp to hours, use hotspot_log.time_ms / 1000 + stamp to generate a datetime.

[chriswhocodes]

Thanks, good idea. Will make it easier to correlate with other log files.

[chriswhocodes]

Implemented back end of this feature in 3267326

Now need to add options in UI to view log timestmpas as absolute time.