Add a "latency" stat in the dashboard
Stats: Rename latency to default_latency

Since it reflects only the latency of the default queue
it's more expressive like this.
Merge pull request #1230 from jlecour/latency_stats

Add a "latency" stat in the dashboard
Use new celluloid/test.rb

This reverts commit 1e24e783a041d64bef2550287f6272ed7cf491ba.
Merge pull request #1233 from mperham/celluloid-test

Use new celluloid/test.rb
don't fail when handling an exception with a nil backtrace
Merge pull request #1234 from musicglue/nil_exception_backtrace

don't fail when handling an exception with a nil backtrace
Merge remote-tracking branch 'upstream/master'