Fixing bug where changing a user's password would cause that user's role to be demoted to USER. Also adding a check to ensure that if there is only one ADMIN account, that that account cannot be demoted to USER.

Fixes #11
Merge pull request #13 from chriscasola/fix-user-update

Fixing bug where changing a user's password would cause that user's role...
Merge remote-tracking branch 'upstream/dev' into dev