Tidy up "services_captiveportal_vouchers" XHTML

Add closehead varaiable, move script into HEAD and close HEAD manually
Add BODY
Remove unordered list tag
Update HTML Boolean Operators
Close INPUT
Deprecate ampersand
Close IMG and add ALT
Add CDATA sections to script
Merge pull request #1050 from ExolonDX/branch_master_07

Tidy up "services_captiveportal_vouchers" XHTML