Fix guide index's link to custom form
Update to latest Asciidoctor version

We will temporarily remove PDF support until the plugin supports it.
spring4Test uses Spring 4.0.0.RC1
XsdDocumentedTests now uses asciidoc instead of asciidoctor
Remove checkRepositories
WebSecurityConfigurerAdapter implements WebSecurityConfigurer
Release version 3.2.0.RC2
Next development version
Fix guides spec
SEC-1932 Added PBKDF2PasswordEncoder.

 - Also moved some logic into a new class, AbstractPasswordEncoder. Both PBKDF2PasswordEncoder and the now-simplified StandardPasswordEncoder extend AbstractPasswordEncoder.
 - Added tests for PBKDF2PasswordEncoder .