- Change the way activation_key is created:
* get the first 20 characters of the some_kind_of_hash(salt+username)
* encode mail with base64
* combine these two and create the activation_key

- add info about URLsafe base64 encoding/decoding func.s
Add list_display for UserProfileAdmin in admin.py
Implement send_verification for change_email address.
Increase activation_key fields length to 60 characters, due to the changes made.
change the name of the confirm verification page in urls.py
Change email is implemented.