Admin: change titles in the user list

1.) Change Pins column to be called Added. Added is the # of items added by the user. Change Repins to Added from.

2.) Remove Friends column, we will not have friends for launch. Just follows and followers.

3.) Add user's username, email in that table.

so that it shows the user's username, email in that table.

Table header row should be:  Name     Username     Email    Added    Added from   Followers   Follows     Date Created.
Merge pull request #38 from camilotorresf/admin-users-search

Admin: change titles in the user list