Notify class and method name of failed Delayed::Job

For better error visibility of delayed_job failures, notifying an object class name as a component and a method name as an action. This will make delayed job errors from different class/methods reported separately on www.honeybadger.io. 

For instance, both `1.delay.+("")` and `"".delay.+(1)` raise `TypeError`, which will be reported separately as below.

## Current

`1.delay.+("")` and `"".delay.+(1)` 

![error__8497101_in_wantedly_-_honeybadger](https://cloud.githubusercontent.com/assets/43811/4501554/9e0369e8-4aae-11e4-9859-1a44abb96f28.png)


## With the change

`1.delay.+("")`

![error__8497061_in_wantedly_-_honeybadger](https://cloud.githubusercontent.com/assets/43811/4501515/cdb0b886-4aad-11e4-86d5-4c1174f3abd5.png)

`"".delay.+(1)`

![error__8497085_in_wantedly_-_honeybadger](https://cloud.githubusercontent.com/assets/43811/4501512/a6560ade-4aad-11e4-8477-473db8ef2fa3.png)