BUGFIX: Reap immediately after initialization on startup

[shdunning]

Possible fix for #55.

These changes allow the first reap cycle to cleanup dead pools and any associated stale lock info. 2 main changes:

• shorten the deadTime from 5 minutes to 10 seconds (2X heartbeat period)
• first reap cycle begins after some initialization time during process startup (currently deadTime, or 10 seconds)
• don't expire heartbeat keys ever, which delegates this responsibility to the reaper

[shdunning]

@tylerb can you try this out in your testing to see if it helps address #55 ?

[tylerstillwater]

I'll give this a go and let you know. Thanks!

[tylerstillwater]

@shdunning I have just deployed this and it appears to be working just fine. Thank you for taking a look. Much appreciated!

[shdunning]

Awesome, glad to hear it! I tested in our staging and it's behaving as expected. I'm going to merge this and close out issue #55.