Empty email for users gets saved as an empty string

The actual behavior is that horizon sends an empty string
on the "email" field when creating a new user if the field
isn't filled by the user.
To match the keystone client behaviour, instead of sending
an empty string, this patch sends a "None" value when the
field isn't filled by the user.
By doing this, when creating a new user from both,
keystone client and horizon, a "null" value is stored
under the same conditions.
in the database. This will keep the data consistency.
From the presentation point of view, when a "null" value
is received, it is presented as an empty string instead
of showing "None" on the "email" field of the users table.

Change-Id: Ib5df774b3fe9d82c084f380c9c11aea46b2984aa
Closes-Bug: #1265805
The order of fields have changed for update default quota form.

Changed the ordering of the the fields for update default quota form
so that it now matches the default quota table page.

Change-Id: I76c5b75f30d9db39c83b395bffbf11340b2e0bde
Closes-Bug: #1275892
Merge "The order of fields have changed for update default quota form."
Merge "Empty email for users gets saved as an empty string"