Admin-user can change password

[Tai-T]

As an admin-user, I want to be able to change my password to protect the security of my account.

Acceptance criteria

• Password has to have 12+ characters. At least one character of each: 1 lower case, 1 upper case, 1 number, 1 special char: !%@#
• Fields are: enter current password, enter new password, confirm new password
• Error messages on entering: wrong current password, non-matching new passwords, new password that doesn't meet criteria outlined above.

[quivop]

netahe's comment today reminded me to add that this issue, along with #3, #4, #6 and #7 are all issues that basically need the default django implementation tested, as well as perhaps some minor customizations to add helpful/descriptive text for the user.