Add a 'form-parameter' attribute to <remember-me>

This change extends the namespace configuration of <remember-me>
with a 'form-parameter' attribute. The introduced attribute sets
the 'parameter' property of  AbstractRememberMeServices.

This enables overriding the default value of
'_spring_security_remember_me' using the namespace configuration.

Additional changes:
* Map the default schema location spring-security.xsd to the
  3.2 version (spring-security-3.2.xsd)

Issue: SEC-2119