Changed Cucumber tags according to the convention

* Replaced @phantomjs-bug with browser specific tags (@firefox
@internet_explorer_10 @phantomjs).
* Replaced @custom-browser tag with @clean tag.
* Deleted cucumber.yml file since it is no longer used.
* Replaced old (no longer implemented) step names with new ones

The convention:

https://www.mediawiki.org/wiki/Manual:Coding_conventions/Selenium#Requir
ed_tags

Paired with: Kartik Mistry
Bug: 60335
Bug: 62477

Change-Id: I54f9ccbaaeb843293fbc1608d53f0e12b6d74cbe
Merge "Changed Cucumber tags according to the convention"