Added documentation showing how to set attributes on MultiCheckboxes and Radio options.

Signed-off-by: Chris Burnham <chris@burnhamup.com>
Merge pull request #1047 from burnhamup/fix/zend.form.element.multicheckbox

Added documentation showing how to set attributes on MultiCheckboxes and...
[#1047] CS fixes

- Substitute 4 spaces for all tabs
Merge branch 'hotfix/1047'

Close #1047