Adding test for Referrers distinct metric and fixing couple failing tests.

tests/PHPUnit/System/ImportLogsTest.php

@@ -38,6 +38,11 @@ class ImportLogsTest extends SystemTestCase
                                'date'    => '2012-08-09',
                                'periods' => 'month')),
 
+            array('Referrers.getNumberOfDistinctWebsites', array('idSite'  => self::$fixture->idSite,
+                                                                 'date'    => '2012-08-09',
+                                                                 'setDateLastN' => true,
+                                                                 'periods' => 'day')),
+
             array('MultiSites.getAll', array('idSite'   => self::$fixture->idSite,
                                              'date'     => '2012-08-09',
                                              'periods'  => array('month'),

tests/PHPUnit/System/expected/test_ImportLogs__Referrers.getNumberOfDistinctWebsites_day.xml

+<?xml version="1.0" encoding="utf-8" ?>
+<results>
+	<result date="2012-08-09" />
+	<result date="2012-08-10" />
+	<result date="2012-08-11" />
+	<result date="2012-08-12" />
+	<result date="2012-08-13">1</result>
+	<result date="2012-08-14" />
+	<result date="2012-08-15">3</result>
+</results>
\ No newline at end of file

tests/PHPUnit/System/expected/test_OneVisitorTwoVisits__Referrers.getNumberOfDistinctCampaigns_day.xml

 <?xml version="1.0" encoding="utf-8" ?>
-<result>1</result>
+<result>0</result>
\ No newline at end of file

tests/PHPUnit/System/expected/test_OneVisitorTwoVisits_withCookieSupport__Referrers.getNumberOfDistinctCampaigns_day.xml

 <?xml version="1.0" encoding="utf-8" ?>
-<result>1</result>
+<result>0</result>
\ No newline at end of file