Add support for alias records

This PR adds making possible to add `alias` records on [route53](http://docs.aws.amazon.com/Route53/latest/DeveloperGuide/HowToAliasRRS.html) via [API](http://docs.aws.amazon.com/Route53/latest/APIReference/API_ChangeResourceRecordSets.html#API_ChangeResourceRecordSets_RequestAliasSyntax) with underlying fog library.  

In this [commit](https://github.com/fog/fog/commit/fa448bc02c15afabd2a324501e694ca034dcd5ac) fog supports sully adding/deleting alias records, that comes without `ttl` and with `alias_target` hash option.

##### Tasks performed

- [x] Support `alias_target` option in provider, this is passed as is to fog.
- [x] Add second test to test alias records and extract configuration to yaml file, configurable to run
- [x] Remove constant redefinition, fog full require and code refactor