MIS update (Student registration) and Bug fixes


**Functionalities implemented:**

**1) MIS: Validation update for ```registration_date``` field**
 
   - Maximum date limit as current date added
   
   - File modified:
   
     1) templates/ndf/student_create_edit.html
     
**2) MIS: Validation update for ```email_id``` field**
 
   - Instead of using html5's in-built input email-type element's check, now implemented regular-expressions check!
   
   - File modified:
   
     1) ATs.csv
     
        - Updated email_id AttributeType: Now validators field consists of following value - ["email", "^\w+([\.-]?\w+)*@\w+([\.-]?\w+)*(\.\w{2,3})+$"]
    
     2) templates/ndf/html_field_widget.html
     
        - validators field's 1st-index value populated in pattern attribute of input(type=email) html element
   
**3) Bug fix: Dashboard url redirection**
 
   - Bug was:
   
     - First login via any user. [1st tab]
     
     - Now open user's dashboard on another tab [2nd tab]

     - Close 1st tab; and refresh 2nd tab.. you will get a following error:
     
       - AttributeError: 'AnonymousUser' object has no attribute 'date_joined'
       
     - This is because an Anonymous user is accessing an authenticated user's view!
     
   - So in order to resolve that just added login-decorator for that view. Now it redirects user to log-in view.
   
   - File modified:
   
     1) views/userDashboard.py
     
**4) Bug fix: Redirection to previously visited page after user logs-in**
 
   - templatetag created: ```check_accounts_url(path)```
   
     - Checks whether the given path is of accounts related or not
      
       - Accounts means regarding login/logout or password-reset and all!

  	 - Arguments:

       1) path -- Lastly visited url by the user taken from request object

     - Returns:
	     
       1) A boolean value indicating the same
       
   - If the value returned by this function is false, then only redirection-url is appended to login-url.
   
   - Files modified:
   
     1) templatetags/ndf_tags.py
     
     2) templates/ndf/base.html