Use monotonically increasing integers for ids

Merge pull request #5 from rkallos/upkeep/monotonic-ids

Use monotonically increasing integers for ids

Use monotonic timestamps in #wrek_event

In addition, I also enabled Travis CI.

Upgrade erlexec to 1.7.4

As a result of this issue, it was brought to my attention that I was using an old version of erlexec. This release now uses the latest tagged release of erlexec; 1.7.4.

Add #wrek_event (now with timestamps!)

I'm bumping the major version because the change to wrek_event is not backwards-compatible.