Adding display name attribute, updated UDS libraries

Updated UDS services libraries to newer uds-person-client-java 2.0, and the 1.2 uds data model that includes access to preferred name. Also added displayName attribute to UWUserDetails that should be picked up from Shibboleth displayName header.

Also setting UwframeSession to use displayName as displayName if it's non-null, else using fullName for displayName as it used to do.

When constructing displayName from a UDS Person, it prefers the name.preferredFirstName(). if that is null, falls back to firstName. Either is prepended to last name for the displayName property if using UDS Person integration.

I bumped it to 1.8.0-SNAPSHOT from 1.7.1-SNAPSHOT, since I don't think it's a breaking change. However, since it does change the artifacts it imports (the UDS ones), it might break something after all. However again, I see promises in the comments and ReadMe about new features that should be available in the 2.0 release that I wasn't prepared to add yet. So advice on the versioning would be appreciated.

Tapping @bjsousa and @paul.erickson and @andrew-summers on this MR, since I see commits from all of you in the history.