Create script or rake task to audit steps usage

• Steps that are unused might be untested and not working. Finding orphaned steps might help ameliorate this.
• An audit could tell you which steps are used by the most number of scenarios, and thus informing the decision to introduce a change.

For example:

rake audit:steps
unused:
            /lib/steps/my_steps.rb:17 Then /^I click the Pay Now button$/
most used:
3342 times: /lib/steps/my_steps.rb:35 Then /^I click the logoff button$/

rake audit:pages
unused:
            /lib/pages/my_page.rb:22 :footer_table