added missing DAOs for diverse entity types
added documentation on class level
merged from gitlab

Merge branch 'master' of 10.6.9.195:missy/disco-persistence-api
added DAO for PeriodOfTime
added DAO for period of time
removed dependency to spring-core
merged
refactored old disco model type
merged from upstream

Merge branch 'master' of 10.6.9.195:missy/disco-persistence-api
added NoteDAO
new parent version
extracted to gesis-ddi-persistence module
new parent version
extracted to gesis-ddi-persistence
initial commit
refactoring package name
merged from remote

Merge branch 'disco-0.0.8' of 10.6.9.195:missy/disco-persistence-api into disco-0.0.8
New branch org.gesis.ddi.Identifiable-move with 0.0.10-SNAPSHOT
IdentifiableDAO moved
added getByURN