Add quote for bug report name so Win is happy. (#398)

diff --git a/mobly/controllers/android_device.py b/mobly/controllers/android_device.py
index 516df6e..9c6305d 100644
--- a/mobly/controllers/android_device.py
+++ b/mobly/controllers/android_device.py
@@ -1060,7 +1060,7 @@
             # shell=True as this command redirects the stdout to a local file
             # using shell redirection.
             self.adb.bugreport(
-                ' > %s' % full_out_path, shell=True, timeout=timeout)
+                ' > "%s"' % full_out_path, shell=True, timeout=timeout)
         self.log.info('Bugreport for %s taken at %s.', test_name,
                       full_out_path)