Tidy up password change form and indicators

* Add bootstrap 3 form classes
* Bootstrap 3 form ‘add-ons’ behave differently, you can’t toggle the
display on and off so easily. Instead show a greyed out ‘ok’ sign,
which is replaced with a green or red symbol depending on input
* Render help text in an alert, and remove icons for better legibility
* Use friendlier green and red colours for ok/not-ok symbols
Tidy up edit your account forms

* Add bootstrap 3 form classes