Change default error icon to a standard JUI icon
Use Prev instead of Previous
Second partial fix

This is a commit of a partial solution for testing. This fix makes the
error display and submit buttons work correctly (at least on F3.1b on
bootstrap templates).

To Do:
1. Fix repeat group duplication with events.
2. Apply same page validation and button enabling to bootstrap tab
templates.
3. Do bootstrap validation tooltips if decided to have these.
4. Fade effects for page and field shows / hides if desired.
5. Change button classes with pagination i.e. primary button is Next
until last page. Apply bootstrap classes to other buttons.
6. Tidy up