ver Jan9th

implemented get_accessibility_tree to convert the accessibility tree
  from pyatspi to an xml format similar to view hierarchy and HTML
havn't merged into server/main.py
tested the AT structure of main window of Thunderbird

desktop_env/evaluators/getters/__init__.py

@@ -1,3 +1,3 @@
 from .file import get_cloud_file, get_vm_file, get_cache_file
-from .misc import get_rule
+from .misc import get_rule, get_desktop_path, get_wallpaper, get_accessibility_tree
 from .vlc import get_vlc_playing_info