Situations now point to (rather than embed) a SituationMention

to mirror the behavior of Entity, EntityMention, and EntityMentionSet
(*MentionSet embeds the *Mentions and the *s point to those *Mentions)
bumped version to 1.0.12-SNAPSHOT
Merge branch 'master' of github.com:hltcoe/concrete
Merge branch 'master' of github.com:hltcoe/concrete