LP1797025 Allow patrons to add/edit their preferred name

LP1797025 Allow patrons to add/edit their preferred name

Fixed issues pertaining to the previous commits. Listed on #12 of the launchpad bug.
1a - if a Preferred name is set, the field displays twice. This has been
fixed and now displays only 1 set of preferred names.
2 - "Update Username" now displays "Update Preferred Name"
3 - Removed the display of preferred names on the form as it was a bit
  redundant.

Signed-off-by: Scott Angel <scottangel@mobiusconsortium.org>