add badges for circle and dependencies to Readme

add readme badges for:

* dependencies [![Dependencies](http://allthebadges.io/netguru/help/gemnasium.png)](http://allthebadges.io/netguru/help/gemnasium)
* Circle CI status ![Circle CI](https://circleci.com/gh/netguru/help/tree/master.png?circle-token=0b87a42d881a82d69dca72d9c0f4cc680f795f62)

do we want to add coverage status as well? travis or coveralls? what do you think?