title: Cucumber reports getting overwritten when a new feature file is executed
body: <p>I am writing a test suite and have came across an issue. I am using cucumber and have defined multiple feature files. When I run the test pack the progress (html report and json format) of one feature file gets over-written when the next feature file execution begins.</p>
  
  <p>I have multiple test classes defined that runs these feature files. I am trying to find a way I can get a single html report for all feature runs to give a consolidated view.</p>
  
  <p>Sample test files for ref:</p>
  
  <pre><code>@CucumberOptions(plugin = { "pretty", "html:target/report/html",
  "json:target/report/json/result.json" })
  public class BaseFeature {
  
  }
  
  @RunWith(Cucumber.class)
  @CucumberOptions(features = "classpath:test/feature/rest/query.feature"
  , monochrome = true
  , glue={"a.b.c.rest"})
  public class RunTest1 extends BaseFeature {
  
  }
  
  @RunWith(Cucumber.class)
  @CucumberOptions(features="classpath:test/feature/soap/book.feature"
  , monochrome = true
  , glue="a.b.c.soap")
  public class RunTest2 extends BaseFeature {
  
  }
  </code></pre>
  
  <p>Let know what can be done to have a consolidated report.</p>