Fixed a few bugs related to admin dashboard

1. The form for creating a new application redirects to
/admin_applications, not /admin
2. Added a “add a new application” hyperlink to the admin banner
3. Re-positioned the volunteer user name in the volunteer header (now
in line with other items)
4. In admin tab for applications, re-named ‘More details’ and ‘click
here’ to ‘More details/Update’ to better reflect functionality
5. Added the header for the view for reviewing an application by a
volunteer.
6. Fixed the code for ‘cancel’ for the form for updating the
organization button by admin.