Timed explicit returns

Allow explicit returns in timed blocks. Previously, metrics would not be sent if you explicitly returned from a method from inside a timed block. E.g.

```ruby
$statsd = Statsd.new '::1', 9125
def some_method
  $statsd.time('test') do
    sleep 1
    return "Explicitly returned string" 
  end
end
puts some_method
```