Resolved quite a few file-system encoding/decoding related cases.

In order to resolve the non-ascii characters in path (in user directory,
storage path, etc) on windows, we have converted the path into the
short-path, so that - we don't need to deal with the encoding issues
(specially with Python 2).

We've resolved majority of the issues with this patch.
We still need couple issues to resolve after this in the same area.

TODO
* Add better support for non-ascii characters in the database name on
  windows with Python 3
* Improve the messages created after the background processes by
  different modules (such as Backup, Restore, Import/Export, etc.),
  which does not show short-paths, and xml representable characters for
  non-ascii characters, when found in the database objects, and the file
  PATH.

Fixes #2174, #1797, #2166, #1940

Initial patch by: Surinder Kumar
Reviewed by: Murtuza Zabuawala

web/pgadmin/utils/html.py

@@ -10,9 +10,14 @@
 """Utilities for HTML"""
 
 import cgi
+from pgadmin.utils import IS_PY2
 
 
 def safe_str(x):
-    return cgi.escape(x).encode(
-        'ascii', 'xmlcharrefreplace'
-    ).decode()
+    try:
+        x = x.encode('ascii', 'xmlcharrefreplace') if hasattr(x, 'encode') else x
+        if not IS_PY2:
+            x = x.decode('utf-8')
+    except:
+        pass
+    return cgi.escape(x)