Changed qnetworkdiskcache unittest to cleanup test directory.

- Remove foo directory tree after run.

Change-Id: I2d554b4c64fc7162c7717c840534cf77f5e744d0
Reviewed-by: Kurt Korbatits  <kurt.korbatits@nokia.com>
Reviewed-by: Jason McDonald <jason.mcdonald@nokia.com>
Reviewed-by: Rohan McGovern <rohan.mcgovern@nokia.com>

tests/auto/network/access/qnetworkdiskcache/tst_qnetworkdiskcache.cpp

@@ -186,6 +186,9 @@ void tst_QNetworkDiskCache::initTestCase()
 // It is only called once.
 void tst_QNetworkDiskCache::cleanupTestCase()
 {
+    QDir workingDir("foo");
+    if (workingDir.exists())
+        workingDir.removeRecursively();
 }
 
 // This will be called before each test function is executed.