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

[rwinch]

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] #1