Browser local storage support for Favorite tables feature.

After this commit:
- If "pmadb" is available, then browser's localStorage will be updated with "Favorite tables" from pmadb or if pmadb is empty, then it will be updated with localStorage's entries.
- If "pmadb" is not available, then "Favorite tables" will be loaded from localStorage and new tables will be added to localStorage only.

Signed-off-by: Ashutosh Dhundhara <ashutoshdhundhara@yahoo.com>