Create SSH keys for SSH clone Spinach tests

These tests would check if the "This project is empty" banner would
contain SSH clone URLs. Oddly enough this should have never passed (as
far as I can tell) as SSH clone URLs in this banner are _only_ displayed
if the current user has at least 1 SSH key attached. Since the tests
never seem to create any they never should have passed, yet somehow they
did. To solve this the Spinach tests in question now ensure at least 1
SSH key is present.

features/project/issues/issues.feature

@@ -160,6 +160,7 @@ Feature: Project Issues
 
   Scenario: Issues on empty project
     Given empty project "Empty Project"
+    And I have an ssh key
     When I visit empty project page
     And I see empty project details with ssh clone info
     When I visit empty project's issues page

features/steps/project/issues/issues.rb

@@ -5,6 +5,7 @@ class Spinach::Features::ProjectIssues < Spinach::FeatureSteps
   include SharedNote
   include SharedPaths
   include SharedMarkdown
+  include SharedUser
 
   step 'I should see "Release 0.4" in issues' do
     expect(page).to have_content "Release 0.4"