[#21] Added support for multiple order by fields as well as 'asc' and 'desc' sort order.
[#21] Added tests for mongodb ordering.
[#21] Support for sorting in MongoDB.
[#21] Fixed elvis comments.
[#21] Added entry to README.
Merge pull request #95 from inaka/jfacorro.21.order.asc.desc

[#21] Support for sorting asc/desc