Bug fixed regarding url & subscription policy, Updated changes in privacy for resources.

Bug fixed regarding regular expressions in user name.

Modification in :
``` urls --> user.py ```

Implemented resources privacy according to user groups.
From now onwards resources created by user in any group will be reflected in users own group as the creator of resource is the user itself.
All privacy policies implemented accordingly

 Modification in :
 ```
page_list.html
user.py
ajax_views.py
file.py
forum.py
methods.py
page.py
quiz.py
```

Bugs resolved for displaying subscribed group in group dashboard.
As of now , if user is subscribed in some group and if its a private group then that user can see that subscribed group in his group dashboard along with users own public and private groups.

Modification in :
```
ndf_tags.py
group.html
```
Added script for already created resources:
This scripts runs through all resource documents along with their groups and inserts username into their group_set field , so that previously created resources should also visible in their particular user groups.

( Note: Fire this command "python manage.py add_policy"  then "python manage.py update_group_set" )