Added `filterByData` method and its test.

Suggestion to improve the **kue**'s search capabilities by providing a method capable of filtering jobs from `type` in `state` having job.data which deeply equals a `condition` object.

This filter is useful for finding duplicates, answer questions related to search and could be used to solve problems like: #471, #440, #376, #267.

For usage see its [test](https://github.com/ColorfullyMe/kue/blob/filterByData/test/test.js#L58).