SES-98: Update Spring to 3.0.7 and Spring Security to 3.1.0

Since this has not been released yet and it has conflicts when updating to Spring Security 3.1, just update minimum requirement to 3.1.

I realize there is already a pull request [1] for this but it results in the following compilation error:

    [ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:2.0.2:compile (default-compile) on project spring-security-kerberos-core: Compilation failure
    [ERROR] /home/rwinch/git/spring-security-kerberos/spring-security-kerberos-core/src/main/java/org/springframework/security/extensions/kerberos/KerberosServiceAuthenticationProvider.java:[91,15] cannot find symbol
    [ERROR] symbol  : constructor KerberosServiceRequestToken(org.springframework.security.core.userdetails.UserDetails,java.util.Collection<capture#221 of ? extends org.springframework.security.core.GrantedAuthority>,byte[])
    [ERROR] location: class org.springframework.security.extensions.kerberos.KerberosServiceRequestToken

[1] https://github.com/SpringSource/spring-security-kerberos/pull/1