Change UI to show that password is required to make changes

[corajr]

There were at least two possibilities regarding the user profile update:

1. change the UI to indicate that the password is required to update any field
2. separate the form out into a sensitive (password, email) and non-sensitive section by:
   • creating a new controller to manage user profile
   • overriding RegistrationsController#update to check if any sensitive attributes are changed (use update_with_password if so or update_without_password otherwise

Option 1 is more readily achievable and doesn't require a bunch of new tests, but option 2 is still possible.

[mooreniemi]

Option 1 is good initial solution for newbie.