Improve Listen warning when block raise an execption (add backtrace)

#138
Move CHANGELOG to Girhub releases page
Release 1.3.1
Update CHANGELOG.md
Merge branch 'master' into v2.0

Conflicts:
CHANGELOG.md
lib/listen/listener.rb
lib/listen/version.rb
spec/listen/listener_spec.rb
Merge branch 'master' into v2.0

Conflicts:
	CHANGELOG.md
	lib/listen/listener.rb
	lib/listen/version.rb
	spec/listen/listener_spec.rb