Verk 0.11.0

• Add Worker.current_job #52
• Add credo #56
• Reset QueueStats started counters when WorkersManager start #50
• Make WorkersManager timeout configurable #57. Thanks to @mitchellhenke 🎉 !
• Add a random amount of timeouts to WorkersManager timeout #60. Thanks to @mitchellhenke 🎉 !
• Fix wrong stacktrace formatting #61. Thanks to @mitchellhenke 🎉 !
• Refactor Queue, SortedSet and RetrySet #53 #62 #63. Thanks to @krasio 🎉 !
• Change Verk.Log to show down to milliseconds if less than 1 second #55. Thanks to @mitchellhenke 🎉 !