updated the gcs files used in Usage [(#960)](GoogleCloudPlatform/python-docs-samples#960)

updated the gcs files used in Usage to use public ones. Hopefully the readme will be updated

Author: merla18

samples/analyze/analyze.py

@@ -19,11 +19,11 @@
 
 Usage Examples:
 
-    python analyze.py faces gs://cloudmleap/video/next/volleyball_court.mp4
-    python analyze.py labels gs://cloudmleap/video/next/fox-snatched.mp4
+    python analyze.py faces gs://demomaker/google_gmail.mp4
+    python analyze.py labels gs:/cloud-ml-sandbox/video/chicago.mp4
     python analyze.py labels_file resources/fox-snatched.mp4
-    python analyze.py shots gs://cloudmleap/video/next/gbikes_dinosaur.mp4
-    python analyze.py safe_search gs://cloudmleap/video/next/animals.mp4
+    python analyze.py shots gs://demomaker/gbikes_dinosaur.mp4
+    python analyze.py safe_search gs://demomaker/gbikes_dinosaur.mp4
 
 """