CHANGELOG: Add Duration.measure change

Update date and add tag link

Revert to CLOCK_MONOTONIC

Auto-selecting something "better" is a can of worms I am firmly
re-closing.

CHANGELOG tweaks

skip-checks: true

Tests: Expand allowed sleep duration range

Just had JRuby fail with 4.5ms for a 10ms sleep.

0.7.0

v0.6.1 - whoops

Bump to 0.5.0

Tweak README

Add some more duck typing around #to_nanos for Durations