SSP-2465 Fixed missing refUrl encoding, removed UrlBuilderService from persistence context, converted SsoController to use UrlBuilderService
SSP-2460 Fixups from code review

Highlights:

 - Minor inlined doco/comment cleanup
 - Explicit default UrlTemplate
 - UrlTemplates rooted in '/'
 - issueUrl() renamed to buildUrl()
 - buildUrl() returns "login-less" URL if no SSO ticket
 - use issueTicket(username,secret) from SsoController
   (to centralize SsoTicketImpl init)