Improve the Maven build.

There should be three projects.

common, ntlm and spnego

ntlm and spnego can depend on common.

A fourth project will pull these three into one jar and have integration code.

The negotiation toolkit will remain as a fourth project.

Instead of the empty parent project use the fourth project to hold the version info, the fourth project should also pull in the other modules.

The pom in the parent folder will just pull in the fourth project which will pull in the rest.